For the mushroom layer, melt the butter in a large frying pan over medium heat. Sautee onion and garlic in the butter until softened and transparent, about 5 minutes. Add the mushrooms and olive oil and sautee until the mushrooms shrink and wrinkle slightly, about 10 minutes. Remove the mushrooms and onion with a slotted spoon and place in a small bowl. Set the bowl aside.

For the cheese layer, add 1/4 cup butter to the pan and allow it to melt. Add the flour, 1 tablespoon at a time, whisking constantly until a roux forms. Stir the roux in a large bowl with the ricotta cheese, milk, thyme, sage, oregano, black pepper, and salt. Set aside.

Toss the quartered crimini mushrooms with the olive oil and salt in a medium bowl and set them aside.

Preheat the oven to 375 degrees Fahreheit. Bring a large pot of water to a boil. Place some of the lasagna noodles in the water and allow to cook until slightly bendable, about 3 minutes, working in batches as necessary. Remove with tongs and place three to four of the noodles on the bottom of a roughly 9 x 13-inch rectangular casserole dish, keeping them in a flat even layer.

Spread 1/4 of the sautéed mushroom mixture over the noodles, then sprinkle with 1/4 of the grated cheddar cheese. Spread 1/4 of the ricotta mixture over the cheddar, then place 3 to 4 noodles in an even layer on top of the ricotta. Repeat until you have used all of the sautéed mushrooms, cheddar, and ricotta, but do not place noodles over the top and final layer of ricotta. Instead, evenly distribute the quartered mushrooms over the top and sprinkle with a pinch of black pepper. Place the pan on a baking sheet and place the baking sheet in the oven. Cook until the cheese is bubbly around the edges and the mushrooms on top have turned a deep brown and wrinkled, about 45 minutes.

Remove from the oven and cool for 20 minutes before serving.