Prepare the green beans: Bring a large pot of salted water to a rolling boil. Drop in the trimmed beans and blanch for exactly 3 minutes — they should turn a vivid, bright green and still have a crisp snap when you bite one. Immediately drain and plunge them into a bowl of ice water to stop the cooking. Drain again and set aside.

Make the crispy shallot topping: While the beans cool, heat a generous depth of oil in a small pan. Thinly slice 2-3 large shallots or 2 onions into rings, toss them in 60g of flour seasoned with salt and pepper, and shake off the excess. Fry them in batches until they are a deep, amber-brown and the sizzling sound fades to a whisper — about 4-5 minutes per batch. You’ll smell a sweet, toasty fragrance as they turn. Drain on kitchen paper and sprinkle with a little salt while still warm.

Sauté the aromatics: In a large, heavy-based pan or Dutch oven, warm 2 tablespoons of olive oil over a medium heat. Tip in the finely chopped mushrooms and cook, stirring occasionally, until they release their liquid and it has mostly evaporated — you’ll see them turn a deep tan and hear a gentle hiss. This takes about 6-7 minutes. They should smell earthy and nutty.

Build the creamy sauce: Add the minced garlic to the mushrooms and cook for 30 seconds until fragrant. Sprinkle the 60g of flour over the mixture and stir continuously for 1 minute — it will look like a thick, sandy paste. Slowly pour in the oat milk, whisking constantly to prevent lumps. Then add the vegetable stock, soy sauce, dried thyme, and smoked paprika. The sauce will look thin at first, but keep stirring; it will thicken into a smooth, glossy gravy that coats the back of a spoon.

Create the cashew cream: Drain the soaked cashews and add them to a high-speed blender with 120ml of fresh water. Blitz on high for a full 60 seconds until the mixture is completely smooth, silky, and the colour of double cream. Pour this into the pan with the mushroom sauce and stir to combine. Taste and season generously with salt and pepper — the sauce should be richly savoury.

Assemble the casserole: Preheat your oven to 190°C (170°C fan). Add the blanched green beans to the pan of sauce and fold everything together gently until every bean is coated in that luscious, creamy sauce. The beans should look glossy and the sauce should cling to them. Transfer the mixture to a 9x13 inch baking dish and spread it into an even layer.

Bake and finish: Cover the dish with foil and bake for 20 minutes. The aroma that fills your kitchen at this stage is incredible — rich, savoury, and deeply comforting. Remove the foil and scatter the crispy shallot topping evenly over the surface. Return to the oven, uncovered, for a final 10-15 minutes, until the topping is golden and the sauce is bubbling up around the edges. The sound of the bubbles is your cue that it’s perfectly ready.