Heat the olive oil over a medium-high heat in a shallow flameproof casserole or ovenproof frying pan (about 25cm wide) and fry the mushrooms for 7-10 mins until browned. Stir in the shallots and garlic and cook for a few more minutes until fragrant. Pour in the white wine and tomato purée and bubble until reduced and thickened, then season well. Remove from the heat and set aside.

Heat the oven to 200C/180C fan/gas 6. Blitz the wild garlic and milk in a blender until the garlic is finely chopped. Transfer to a jug. Heat the butter in a saucepan over a medium heat and, when bubbling, tip in the flour, mustard powder and nutmeg, and stir to a paste. Cook for 3-4 mins until slightly darkened. Splash in the milk mixture gradually, whisking well after each addition. Bring to a simmer, whisking continuously. Once simmering, whisk for about 5 mins, or until smooth and thick. Season to taste. Will keep covered in the fridge for two days.

Mix the three cheeses together in a bowl. Transfer two-thirds of the mushrooms from the casserole to a bowl, and spread out the remaining mushrooms on the base of the casserole to cover evenly. Pour over a quarter of the white sauce, top with a quarter of the cheese and layer over the pasta sheets – you should be able to fit around four sheets in each layer. Repeat this twice more, then on the final layer of pasta, pour over the last of the sauce and sprinkle with the remaining cheese.

Bake in the oven for 25-30 mins until golden and bubbling. Leave to stand for 10 mins before serving. Serve with a salad in a zingy lemon dressing, if you like.