Preheat oven to 350° F. Lightly grease a 13x9-inch baking dish and set aside.
Bring a large pot of salted water to a boil. Add the pasta and cook according to package directions. Drain pasta into a colander, rinse, drain well and set aside.
Meanwhile, in a large skillet, heat 1 tablespoon of olive oil over medium heat. Add the onion, carrots and bell peppers. Cook, stirring often, until carrots are tender, about 8 minutes.
Scoot the veggies to the edges of the pan and add the ground beef. Increase the heat to medium-high. Cook the beef, crumbling, until browned. Drain off any excess grease.
Add the minced garlic, Italian seasoning, garlic powder, salt and pepper. Cook, sitrring, for 30 seconds.
Stir in the tomato sauce and diced tomatoes.
Remove the pan from the heat. Then stir in ⅓ of the shredded cheese, followed by the cooked pasta.
Transfer to the prepared baking dish. Sprinkle the rest of the cheese over the top of the casserole.
Bake, uncovered, for 20 minutes, until the cheese is melted and lightly golden brown.