Boil pasta in salted water until al dente or semi–hard, drain and set aside.
Heat olive oil in large skillet, add sausage and onion. Cook over medium high heat, stirring to crumble the sausage. Once browned, add garlic and heat for a few minutes. Add the marinara and red pepper flakes. Stir to incorporate all ingredients and bring sauce to a low boil. Stir in the drained pasta, about 10 slices of Fresh Mozzarella and ¾ cup of the Parmesan cheese. Cover and let the combination heat through for a few minutes. Uncover and add the rest of the Fresh Mozzarella slices to the top of the pasta, cover and heat until cheese is melted. Serve immediately topped with remaining Parmesan cheese.