Brown Butter Pesto Lasagna

1. Preheat the oven to 350° F. Lightly butter a 9x13 inch lasagna pan. Cook the noodles according to package directions. 
2. Melt 2 tablespoon butter in a large skillet set over medium heat. Add the mushrooms and season with salt and pepper. Cook undisturbed for 5 minutes or until golden. Add the remaining 6 tablespoons of butter. Allow the butter to brown lightly around the mushrooms for 5 minutes. 
3. Add the garlic, sage, thyme, and chili flakes. Stir in the flour and cook for 1 minute. Add the milk and broth. Bring to a boil and stir for 1 minute. Remove from heat and stir in the provolone and 1/2 cup of parmesan cheese. Stir until the cheese is fully melted and the sauce is smooth. Set the cheese sauce aside.
4. In a bowl, combine the spinach and pesto.
5. Spread 1/4 of the cheese sauce in the bottom of the prepared baking dish. Top with 3-4 lasagna sheets. Spread with 1/2 the spinach/pesto, then another 1/4 of the cheese sauce. Place another 3-4 lasagna noodles on top and then top with the remaining spinach/pesto, 1 cup mozzarella, and another 1/4 of the cheese sauce. Add the remaining lasagna noodles and pour the remaining cheese sauce over top. Top with 1 cup of mozzarella and 1/2 cup of parmesan cheese. 
6. Bake, covered for 30 minutes, then uncovered for 15 minutes more. Let sit 10 minutes before serving.