The 45-minute mushroom roast is the backbone: leeks (~17 min with the boil) + risotto sauté (9 min) + pressurisation (~5–8 min with hot stock in a hot pot) + pressure cook (5 min) + release (~6 min) overlaps it closely, so the tray and the cooker finish within a few minutes of each other — with transitions and stock handling, expect ~45–50 minutes from tray-in to lid-open. The overlap is approximate, not a clock: set a separate 45-minute oven timer when the tray goes in, and pull the mushrooms when it rings or when they’re browned and shrunken. If the cooker runs ahead, pull the tray early only if it’s already browned; pale mushrooms can’t be rescued by the clock. If the mushrooms finish first, hold the tray on the bench, not in the hot switched-off oven — residual heat keeps drying them.
Mise en Place
15:00Oven to 200°C (180°C fan). Line your largest rimmed tray with baking paper and put the 55g butter on it — but only slide it into the oven for the last two minutes of mise, just until melted. Left in through the whole preheat, the milk solids burn and the tray turns bitter.
Knife work: halve and thin-slice the leeks crosswise, then wash the slices well in a bowl of water and drain (grit hides between the layers — wash after slicing). Stem the shiitake and slice the caps 5–8mm thick. Halve and slice one onion lengthwise (mushrooms), chop the other (risotto).
Pour both 500ml cartons of stock (1000g) into a small saucepan with the shiitake stems (plus the 10g porcini and the parmesan rind, if using), lid on, off the heat — it goes on to heat at stage 3, not now; a 40-minute simmer would quietly evaporate the liquid calibration.
Weigh out the rest: grate 70g parmesan; chop 5g parsley; weigh 0.5g dried thyme; measure 175g cream, 120g wine, 12g truffle oil, 5g lemon juice. Cut the 60g butter in half: one half for the sauté, the other cubed and back in the fridge — it must go in cold at stage 6. Get the leek saucepan out now, not at stage 2.
Mushrooms In
3:00Pull the tray with its melted butter. Toss mushrooms, onion, dried thyme, salt and pepper on it and spread into a single layer — overlapping pieces steam instead of brown; split across two trays and swap shelves at each stir if you must. Into the oven, and set a separate 45-minute oven timer now — it, not the stage flow, decides when the tray comes out. Done = tender, browned at the edges, shrunken.
No truffle oil yet — 45 minutes at 200°C would burn off everything you paid for. It goes on after roasting.
Leeks in Cream
15:00Leeks and cream into the small heavy saucepan. Bring to a boil, then start the 15 minutes from when it’s simmering, stirring every few minutes, until the leeks are fully tender and the cream has thickened to a loose purée consistency. Season with the salt and pepper, lid on, off the heat — it gets rewarmed during the release.
Near the end of this stage, give the mushroom tray its first stir.
Risotto Base
9:00Stock pan onto medium heat now, lid on — it needs to be simmering when the rice is ready.
CPE300 on Brown/Sauté. Melt the butter, add the onion, and cook 5 minutes until softening but not coloured (the 9:00 starts when the onion goes in). While the onion cooks: strain the stems (and porcini and rind) out of the stock, top it back up to 1000g with water if straining left it short, and weigh 700g into a jug; lid the rest. Doing this now means the rice never sits dry on the hot element waiting for stock.
Add the rice and toast 2 minutes, stirring, until the grains are translucent at the edges and smell nutty — the leeks and mushrooms are looking after themselves, so the extra minute is free depth. Add the wine, scrape the base clean with it, and cook ~2 minutes until nearly dry — no raw alcohol smell left. A sealed pot can’t cook alcohol off, so it has to go before the lid does.
Pressure
5:00Cancel sauté and immediately pour in the 700g jug of hot stock weighed at stage 3 — the ratio is the recipe, which is why it was weighed, not poured by eye. Salt: 5g in, with Maggie Beer — it carries only ~42mg sodium per 100ml, so the pot is effectively unseasoned without it. Rice only takes seasoning while it cooks, and the finish can’t fix bland grain. On a heavily salted supermarket stock (Campbell’s runs ~13× the sodium) the 5g stays out. Stir once to level, then wipe any grains off the wall down into the liquid — nothing above the waterline, or it scorches during pressurisation. Seal, and pressure cook on Manual, HIGH, 5 minutes (not the Rice button — it runs low pressure).
Pressurisation is quick here — hot pot, hot stock — expect ~5–8 minutes, not the cold-start 10–12. While it climbs, give the mushroom tray its second stir.
Release
5:005 minutes natural release, then release the rest in short bursts — open the valve, close it if it spits starch, repeat until the pin drops. Stand back from the plume. (The CPE300 manual says never quick-release rice; the 5-minute pause plus bursts is the deliberate compromise, because risotto left to full natural release overcooks. See the note below.)
Two minutes into the release, put the leek pan back over low heat to rewarm — earlier and the cream can catch at the edges. When the oven timer rings, pull the mushroom tray and toss with the 12g truffle oil while hot.
Finish
5:00Open the lid and stir the risotto hard for 30 seconds — the agitation you skipped during cooking happens here, and it’s what makes it creamy. Off the heat, beat in the cold cubed butter until it’s emulsified (cold is what makes it thicken instead of split), then the parmesan, then the warm leek mixture. Loosen with reserved hot stock, ~50g at a time, until it flows slowly off the spoon — it should just hold a wave, not stand in a mound, and it thickens further on the plate.
Add the 5g lemon juice — the dish is cream on butter on cheese, and the acid is what keeps the truffle legible past the third bite. Taste: more lemon (up to 10g total) and salt as needed (stock and parmesan vary). Fold in most of the mushrooms, saving a handful to top each bowl. Shaved truffle if using, parsley over the top, serve immediately.
Mixed Mushroom Batch
Shiitake at these quantities is a spend. A 50/50 blend with swiss browns (225g caps each, same slice, same roast) keeps most of the depth at half the mushroom cost. Don’t go below half shiitake — they carry the dish.
Ghee Tray Batch
The fat trio, exactly: 55g ghee on the mushroom tray, 30g butter for the sauté, 30g cold butter for the finish. Ghee has no milk solids and a ~250°C smoke point, so the tray fat can’t turn bitter over the 45-minute roast — melt it on the tray whenever, no two-minute timing care — and its toasted nuttiness suits the shiitake. The sauté and finish stay butter. In a pinch with only one on hand: all-butter is just the main recipe; all-ghee covers the tray and sauté fine, but the finish is the non-negotiable — ghee has no emulsifiers and splits into grease where cold butter thickens, so without butter, lean on the parmesan and reserved stock and accept a looser sheen.
Vermouth Batch
120g dry vermouth in place of the white wine. It keeps indefinitely once opened — no half bottle of sauvignon blanc to justify — and its botanicals sit better against truffle and thyme than a neutral white. Same weight, same near-dry reduction.
Stovetop risotto is 20+ minutes of attended stirring at exactly the moment the mushrooms and leeks also want attention. Under pressure the rice cooks unattended in a sealed pot with no evaporation — which is also why the stock drops from the original’s ~1180g to a flat 1000g. The creaminess comes back in the hard stir at the finish.
The reference (Serious Eats pressure risotto) runs 5 minutes at ~10 PSI with immediate release. The CPE300’s HIGH spans ~6.5–10 PSI depending on load and unit, and this recipe adds a 5-minute natural release, which is not free time — it’s several more minutes of effective cooking. 5:00 + 5NR at 700g stock is the calibrated starting point, deliberately biased toward slightly firm: chalk is recoverable (lid back on, no pressure, 3 minutes; hot stock at the finish), mush is not. If it lands soft, drop to 4:00 before touching anything else. Time and liquid partially trade off against each other — don’t shorten the release and cut the stock in the same adjustment. Log the result and re-dial.
The CPE300 manual says never quick-release rice, and means it — starchy liquid can spray from the valve. Full natural release (10+ minutes) would overcook risotto, so this recipe compromises: 5 minutes natural, then short controlled bursts, closing the valve whenever it spits. Keep face and hands out of the plume, and expect to babysit the valve rather than flip it open.
Rinsing is the usual burn mitigation on this cooker, but here it’s the wrong call: surface starch on arborio is the sauce — rinsing it off gives you pilaf texture in a dish that wants cream. The wine scrape and the weighed liquid do the anti-burn work instead.
Thyme is one of the few herbs that dries well, and this is its ideal deployment: into melted fat for a 45-minute roast, which rehydrates and blooms the dried leaves while burning off exactly the fresh top notes drying would have cost anyway. 0.5g dried ≈ 1g fresh minced — dried runs 2–3× the potency per gram. Whole leaves, no mincing, same moment in the toss. The jar’s age is the real variable: good spice-store stock within 6–12 months of opening, not a long-open supermarket jar. Fresh works as a straight sub at 1g; don’t extend the logic to the parsley, which is fresh or omitted.
The original tosses it on before the 45-minute roast. The aroma compounds in truffle oil are volatile and mostly gone after that long at 200°C — tossing the hot tray with the oil after roasting gets the same coverage with the aroma intact. Buy a small bottle with real truffle in the ingredient list if you can; either way it stales within months of opening.
450g is stemmed cap weight. The original’s “1 lb shiitake, stemmed” is ambiguous about whether the pound is before or after stemming; this recipe reads it as usable caps and says so out loud. Stems run 10–15% of whole weight, so buy ~500–530g and expect 50–80g off. The stems are too fibrous to eat sliced but they’re free stock flavour: they sit in the stock from stage 0 and come out when it’s strained at stage 4.
Don’t hold the stock at a simmer through the whole cook — 40 minutes uncovered evaporates enough to break the 700g/300g split. Stems (and porcini and parmesan rind, if using) in, lid on, off heat at stage 0; heat it at the start of stage 3; strain, top up and weigh into a jug while the onion sautés. If straining leaves you short of 1000g, top back up with water. The porcini and rind are the two biggest flavour levers on the page for zero extra steps — the pot is already there and already being strained.
The leeks hold, covered and chilled, for a day — rewarm before the finish. The mushrooms hold 2 hours at room temperature; re-crisp for 5 minutes in a hot oven if they’ve gone limp. The risotto itself does not hold: cook it when you’re ready to eat.
The named stock is Maggie Beer Vegetable Stock, 2 × 500ml cartons — 1000g exactly, no part-carton. It’s the upgrade over a supermarket carton and it earns it here: real vegetable percentages (onion 9.8%, celery 7%, carrot 6.5%), plus mushroom powder and thyme that land on the same notes as the tray, and a splash of verjuice for acid. At 42mg sodium per 100ml it is effectively unsalted, so the 5g at stage 4 goes in — that is the one mechanical difference from a salted carton (Campbell’s Real Stock runs ~540mg/100ml, roughly 13×, which is why it needed none). 5g into 700g is 0.7% of the cooking liquid and deliberately conservative given 70g parmesan lands at the finish; taste at stage 6 and add there if it reads flat.
Cost is the trade: about $11.80 per litre against ~$4 for the supermarket carton. It is most of the liquid in the dish, so it’s the cheapest place to buy flavour on this page. It stays vegetarian and vegan on its own ingredients (check the parmesan if that matters — traditional parmesan uses animal rennet, and the rind trick follows the cheese), and it contains sulphite preservatives (220, 224) from the verjuice. Chicken stock still works and adds body. Any substitute should taste good enough to sip — and if you swap to a salted one, pull the 5g back out.