Heat 1 tablespoon (10 g) butter and 1 tablespoon olive oil in a large skillet. Add half of mushrooms, season with salt and pepper, and cook for 6-7 minutes, stirring occasionally, until browned and starting to crisp. Transfer to a medium bowl. Repeat with 1 tablespoon (10 g) butter and 1 tablespoon olive oil, and remaining mushrooms.
Sauté pancetta in the same skillet for 4-5 minutes over medium-high flame until golden-brown and crispy. Remove to a paper towel to absorb excess fat.
Return all mushrooms to the skillet and add shallots, wine, and remaining butter. Cook, stirring occasionally, until skillet is dry, about 5 minutes. Return mushrooms to the bowl.
In a small bowl mix and combine ricotta, sour cream, salt and pepper until smooth.
Spread a thin layer of ricotta mixture in a small baking dish (lasagna sheet dimensions) and top with a lasagna sheet. Spread a large spoonful of ricotta mixture over lasagna, scatter some mushrooms and pancetta crumbs over, then a few pieces of mozzarella. Top evenly with some Parmesan and 1 teaspoon marjoram leaves. Repeat layering process (starting with noodles and ending with marjoram) 5 more times; finish with the last of the Parmesan.
Cover lasagna with foil and bake in the oven at 220°C for 20–30 minutes. Remove foil and continue baking until golden brown, 10–15 minutes.