Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking dish.

Melt 2 tablespoons of butter in a medium pot over medium heat and sauté finely chopped mushrooms for about 5 minutes. Add thyme, salt, and pepper, cooking for another 4-5 minutes.

In the same skillet, melt 6 tablespoons of butter and add minced garlic and herbs. Cook for 30 seconds, then whisk in 1 cup of flour for 1 minute. Gradually add white wine and milk, and bring to a gentle boil. Remove from heat and incorporate grated Parmesan and mozzarella.

Bring a large pot of salted water to a boil, add jumbo pasta shells and cook for 2 minutes less than the package directions. Drain and rinse under cold water.

In a mixing bowl, combine ricotta and provolone cheese with the sautéed spinach and mushrooms. Stir until evenly mixed.

Spread 1/3 of the cheese sauce evenly across the bottom of the greased baking dish and fill each pasta shell with the cheese-spinach mixture.

Pour the remaining cheese sauce over the stuffed shells and top with sautéed mushrooms and grated Parmesan.

Cover with aluminum foil and bake for 25 minutes. Remove foil and bake for another 15-20 minutes until golden and bubbly.