01 -  Preheat oven to 375°F and lightly grease a 9x13 inch baking dish. 
 02 -  Boil pasta in salted water until al dente, then drain and set aside. 
 03 -  Heat olive oil in a large skillet over medium heat; sauté chopped onion for 3 to 4 minutes until soft. Add minced garlic and cook for 1 minute. 
 04 -  Stir in drained diced tomatoes, dried oregano, salt, black pepper, and red pepper flakes if desired. Simmer for 5 minutes. Remove from heat and mix in chopped basil. 
 05 -  Whisk ricotta cheese, Alfredo sauce, and whole milk together in a bowl until smooth. 
 06 -  In prepared baking dish, mix the cooked pasta, tomato mixture, and ricotta-Alfredo blend. Stir thoroughly to coat the pasta evenly. 
 07 -  Top evenly with shredded mozzarella and grated Parmesan cheese. 
 08 -  Bake uncovered for 25 to 30 minutes until casserole is bubbling and golden brown. 
 09 -  Let rest for 5 minutes before serving. Garnish with extra basil as desired.