Preheat oven to 350°; spray 4-quart baking dish with cooking spray. Prepare rigatoni as label directs for al dente rigatoni; drain, return to saucepot and cover to keep warm.
In large skillet, cook sausage and onion over medium-high heat 5 minutes or until browned, breaking up sausage with side of spoon. Add garlic, seasoning and fennel seed; cook 1 minute or until fragrant, stirring frequently. Add spinach; cook 2 minutes or until wilted, stirring frequently. Add sauce; cook 3 minutes or until heated through, stirring occasionally. Transfer sausage mixture to saucepot with rigatoni.
Add burrata cheese and mozzarella cheese to rigatoni mixture; toss. Spread rigatoni mixture into prepared baking dish; cover dish tightly with aluminum foil and bake 30 minutes. Remove foil; bake 10 minutes or until edges are bubbly. Makes about 12 cups.
Serve baked rigatoni garnished with parsley, Parmesan cheese and/or crushed red pepper, if desired.
