Preheat oven to 350°F (177°C) and spray a 9x13-inch baking dish with nonstick cooking spray.
Heat olive oil in a skillet over medium heat. Sauté onion and green bell pepper until translucent.
Add garlic and cook for 1-2 minutes until fragrant.
Add ground beef, cook and crumble until no longer pink; drain grease.
Stir in salt, black pepper, Italian seasoning, and spaghetti sauce; set aside.
Cook spaghetti in salted water according to package instructions; drain.
In a separate pan, melt butter and sauté garlic on low until fragrant.
Sprinkle flour over garlic, cook stirring constantly for 1 minute.
Remove from heat, whisk in heavy cream until smooth.
Return to heat, stir in parmesan cheese and cook gently until melted.
Add drained pasta to Alfredo sauce and toss to coat.
Spread coated pasta evenly into the prepared baking dish.
Top pasta with red sauce without mixing layers.
Sprinkle mozzarella cheese evenly over top.
Bake uncovered for about 30 minutes until cheese is melted and bubbly.
Let cool for 10 minutes before serving.
Garnish with fresh parsley and a sprinkle of dried Italian seasoning.