- In large skillet, melt butter over medium heat. Add and cook onions, garlic, thyme, salt, pepper and hot pepper flakes for 8 minutes or until completely softened. Add button and exotic mushrooms; cook, stirring constantly for 15 minutes or until mushrooms are tender and all excess liquid has been absorbed. Stir in spinach and cook for 3 minutes or until wilted. Remove from heat; cool.
- Meanwhile, in large saucepan of boiling salted water, cook manicotti shells for 10 minutes or until tender but firm. Drain and cool under cold running water. Arrange in single layer on damp towel; cover until ready to use.
- Spoon half of tomato sauce into bottom of 13” x 9” (3 L) baking dish. Add cottage cheese, 1 cup (125 mL) of Mozzarella and egg to mushroom filling; spoon ½ cup (125 mL) into each manicotti shell. Arrange snugly in one layer on top of tomato sauce. Spoon remaining sauce over shells. Sprinkle with remaining Mozzarella and Parmesan.
- Bake in centre of preheated 400°F (200°C) oven for 30 minutes or until sauce is bubbling and cheese is melted and golden.
- Casserole can be covered with plastic wrap and refrigerated for up to 24 hours. Add 15 minutes to baking time.