Preheat the oven to 400 degrees F.
Slice zucchini lengthwise into very thin slices using a mandolin or a vegetable peeler.
Chop mushrooms into small pieces and cook them in a pan with olive oil until light golden brown.
Mix the mushrooms and ricotta cheese.
Salt and pepper.
Lay 2 slices of zucchini vertical so they overlap and 2 across to create a criss-cross.
Add 1 tablespoon of the ricotta and mushroom mix in the center and fold all zucchini ends into the center.
Add 1/2 cup of tomato sauce at the bottom of a baking dish.
Place the zucchini ravioli in the dish and top with the remaining tomato sauce and shredded mozzarella cheese.
Bake 30 min