Heat a frying pan with vegetable and butter (75 g) and fry the garlic with mushrooms. Salt and pepper to taste.
Prepare the béchamel. Melt the remaining butter in a saucepan, add the flour and, stirring continuously, gradually pour in the milk. Add salt, pepper, nutmeg, stir and bring the sauce to thicken.
Cook the lasagne sheets until al dente.
Grease a baking dish with oil, lay out the lasagne sheets, spread the sauce, mushrooms and grated cheese evenly on top. Lay out the next layer. Cover with the remaining lasagne, pour over the sauce and sprinkle with cheese. Bake in the oven for 45 minutes at 180°C.