Cook the pasta according to package directions, drain and set aside.
Heat oven to 350° F (177° C).
In a 10-inch skillet over medium-high heat, heat oil 30 seconds. Add ground beef, onions, garlic, Italian seasoning, salt, and pepper. Cook, breaking the ground beef up with a spoon or spatula until the meat is cooked through and no longer pink, about 4 minutes. Drain and transfer ground beef and vegetables to a medium-sized bowl.
Stir in the tomato sauce, sour cream, cooked pasta, and 1/2 cup of the shredded cheese.
Pour into a baking dish lightly greased with butter or oil. Top with the remaining 2 tablespoons of shredded cheese and bake for 20-25 minutes, until cheese is melted.
Remove from oven and serve immediately.
Notes
Choose Lean Ground Beef: Opt for 90% lean ground beef, which offers a balance of taste and reduced grease. This beef has only 10% fat, ensuring flavor without excessive oiliness. If you use a higher fat content beef, remember to drain it on a paper towel-lined plate after cooking to remove excess grease.Shred Your Own Cheese: For the best melting quality, shred your own cheese. Pre-shredded cheeses often contain preservatives that prevent optimal melting, affecting the texture and taste of your casserole.Pasta Flexibility: Feel free to use any pasta you have in your pantry. While penne is suggested, this recipe is versatile enough to work well with various pasta shapes.