Preheat oven to 375°F (190°C) and lightly grease a 9x13-inch casserole dish.
Bring a large pot of salted water to a boil. Cook pasta until al dente, following the lower end of package time. Drain and set aside.
Heat olive oil in a large skillet over medium-high heat. Add onion and bell peppers, cover, and cook 5-7 minutes until softened and translucent.
Stir in tomato paste and minced garlic. Cover and cook 1-2 minutes until fragrant.
Add ground beef, breaking it apart with a spoon. Cover and cook 7-10 minutes, stirring occasionally, until fully browned. Drain excess grease, leaving a little for flavor.
Season with salt, pepper, and Italian seasoning. Stir well.
Add tomato sauce and fire-roasted tomatoes. Cover and simmer 3-5 minutes.
Stir the cooked pasta into the sauce mixture until evenly coated.
Transfer to the prepared casserole dish and sprinkle evenly with shredded cheese.
Bake uncovered for 20-25 minutes, until cheese is melted and bubbly.
Broil for 30 seconds to 1 minute until cheese is lightly golden, watching closely.
Remove from oven and let cool for a few minutes. Garnish with parsley if desired, then serve.
Notes
Cook pasta to al dente since it continues cooking in the oven. Drain most of the grease from the beef but leave a little for flavor. The broiling step should be watched closely to prevent burning. Can be assembled a day ahead and refrigerated; add extra bake time if starting cold. Leftovers keep refrigerated up to 3 days or frozen up to 2 months.
Keyword dinner recipe, ground beef casserole, pepper pasta bake, stuffed peppers pasta casserole