Preheat the oven to 350° F. Grease a 9x13 inch pan.Melt 2 tablespoons butter in a medium pot. Add the mushrooms. Cook undisturbed for 5 minutes or until golden. Add the thyme, and a pinch each of salt and pepper. Cook 4-5 minutes, until fragrant. Remove the mushrooms from the skillet. To the skillet, add the reaming 6 tablespoons butter, the garlic, basil, oregano, and cook 30 seconds or until fragrant. Whisk in the flour and cook for about 1 minute. Add the wine, then the milk. Bring to a boil and stir for 1 minute. Remove from heat and stir in 1/2 cup mozzarella cheese and 1/2 cup of parmesan cheese. Stir until the cheese is fully melted and the sauce is smooth. Set the cheese sauce aside.Bring a large pot of salted water to a boil over high heat and boil the pasta until al dente according to package directions.In a bowl combine the ricotta, provolone, and spinach. Spread 1/3 of the cheese sauce in the bottom of the prepared baking dish. Working with one pasta shell at a time, spoon 1 tablespoon of the ricotta mix into each shell, placing the filled shell into the baking dish as you go. Sprinkle over 1/2 cup mozzarella, pour the remaining cheese sauce over top. Top with a 1/4 cup of parmesan and then the mushrooms. Cover and bake 25 minutes or until the top has bubbled up. Remove the foil and bake another 15-20 minutes. Serve with fresh thyme.