Wash and drain the spinach.
Wash and roughly chop the mushrooms.
Chop the shallots and garlic cloves.
Drizzle a little olive oil into a pan. Heat and add the shallots and garlic. Let it brown for 1 minute.
Add the ricotta and let it melt.
Pour in the milk and add the Parmesan cheese. Add salt and pepper to taste. Mix to obtain a homogeneous sauce.
Add the mushrooms and the spinach.
Cut the lasagna sheets into large pieces. Add them to the pan. Stir and make sure the lasagna is well separated.
Cook for about 10 minutes, until the pasta is cooked al dente.
Serve with grated Parmesan cheese.