Cook pasta according to directions until al dente, omitting salt and fat; drain. Cut each noodle crosswise into 4 pieces, forming 32 squares.
Cook prosciutto in a large skillet over medium-high heat until crisp. Remove prosciutto from pan; crumble. Return pan to medium-high heat. Add oil to pan; swirl to coat. Add shallot; sauté 2 minutes. Add mushrooms; cook 8 minutes, stirring occasionally. Stir in spinach; cook 2 minutes or until spinach wilts. Remove from heat. Drain.
Combine ricotta cheese, Parmesan, 1 1/2 tablespoons thyme, and next 3 ingredients (through fontina) in a large bowl. Add spinach mixture and prosciutto, stirring well to combine.
Coat 8 (6-ounce) ramekins with cooking spray. Place ramekins on a jelly-roll pan. Arrange 1 pasta square in bottom of each ramekin. Spoon one-third of filling evenly over pasta squares; top filling with 1 pasta square. Repeat layers twice, ending with pasta. Combine remaining 1 1/2 teaspoons thyme and mozzarella cheese. Sprinkle evenly over lasagnas.
Cover pan loosely with foil coated with cooking spray. Bake at 350° for 20 minutes. Uncover and bake an additional 15 minutes or until bubbly and browned. Let stand 10 minutes before serving.