01 -
Preheat oven to 350°F and grease a 9x13 inch baking dish.
02 -
Brown Italian sausage in a large skillet over medium-high heat. Add chopped onion and sauté until translucent. Stir in minced garlic and crushed red pepper flakes, cooking until fragrant about 1 minute. Drain excess grease, stir in marinara sauce, and set aside.
03 -
In a large bowl, blend cottage cheese, softened cream cheese, sour cream, grated Parmesan, Italian seasoning, and garlic powder until smooth and creamy. Gently fold in frozen ravioli and 1 1/2 cups shredded mozzarella, coating ravioli evenly.
04 -
Spread half of the sausage marinara mixture in the prepared baking dish. Layer baby spinach evenly over the sauce. Spread the ravioli mixture on top, then cover with remaining sausage marinara sauce. Sprinkle the reserved 1 cup of shredded mozzarella cheese evenly over the top.
05 -
Cover dish tightly with foil and bake for 30 minutes. Remove foil and bake an additional 15-20 minutes, until cheese is melted, bubbly, and ravioli is heated through.
06 -
Allow casserole to stand 10 minutes before serving. Optionally, garnish with chopped fresh parsley or basil.