Cut sausage into 1/2 inch rounds. In a large skillet, brown sausage over medium-high heat, in batches and adding oil if necessary. Transfer sausage to a bowl.
Pour off any fat from pan. Add onions, garlic and red pepper, cook over medium heat, stirring occasionally, for about 5 minutes or until softened. Stir in pasta sauce, tomato sauce, basil, oregano, and fennel seeds; bring to a boil, stirring and scraping up any brown bits from the bottom of the pan. Return sausage and any accumulated juices to pan; cover and simmer for 15 minutes or until sausage is firm throughout.
Meanwhile, in a large pot of boiling salted water, cook pasta for 6 minutes, add spinach to boiling water; cook for 1 minute. Drain well and return to pot. Add sausage mixture and provolone/mozzarella cheese; stir to combine well.
Transfer to 2 greased 8-inch square baking dishes or 1-13x9 inch dish. Sprinkle with asiago/parmesan cheese. Cover dish with greased foil, greased side down.
***THIS IS WHERE YOU FREEZE THE RECIPE WITH EXCELLENT RESULTS***
To serve: Bake covered with foil, in a 375 degree F. oven for 30 minutes or for 1 hour if from the refrigerator. This freezes beautifully (thaw in refrigerator before baking)