Layers of gluten-free sheets, garlicky mushrooms, wilted spinach and a cornflour bechamel that never goes lumpy.
Prep
30 mins
Cook
50 mins
Servings
6
Per serving
£1.63
Difficulty
medium
A vegetarian lasagne with enough savoury depth that nobody asks where the meat is. The bechamel is thickened with cornflour rather than a wheat roux, which is faster, more forgiving and completely coeliac safe.
Cover the dried porcini with 200ml just-boiled water and leave for 15 minutes. Lift them out, chop finely, and keep the soaking liquid, leaving the gritty last spoonful behind.
Heat 2 tablespoons of oil in a large frying pan over a high heat and fry the chestnut mushrooms in two batches for 5 minutes each, until browned and squeaky rather than grey and wet.
Turn the heat down, add the last tablespoon of oil, the onion and thyme, and cook for 8 minutes. Stir in the garlic, chopped porcini, the strained soaking liquid and the tomatoes, and simmer for 10 minutes until thick. Season.
Wilt the spinach in a dry pan in batches, then tip into a sieve and press out as much liquid as you can. Chop roughly and stir into the mushroom mixture.
Wet spinach is the main cause of a sloppy lasagne. Press it until it looks almost dry.
For the bechamel, melt the butter in a saucepan. Whisk the cornflour into 100ml of the cold milk to make a smooth slurry, then pour the rest of the milk into the butter and heat until steaming. Whisk in the slurry and cook, whisking, for 3 minutes until thick. Season with nutmeg, salt and pepper.
Heat the oven to 180C fan. Spread a thin layer of bechamel in a 30 x 20cm dish, then layer pasta sheets, mushroom mixture, bechamel and a little hard cheese. Repeat for three layers, finishing with bechamel.
Scatter over the mozzarella and remaining hard cheese and bake for 45 to 50 minutes until bubbling and browned. Rest for 15 minutes before cutting.
Gluten-free sheets absorb liquid more slowly than wheat ones, so a generous bechamel and a proper rest are what stop it collapsing on the plate.