Cook the pasta in a large pot of salted boiling water until al dente, about 8 minutes. Drain and set aside.

Brown the ground beef in a large skillet with olive oil over medium-high heat for 5-7 minutes, breaking it apart until fully cooked. Drain excess fat.

Sauté diced onion, carrot, and celery in the same skillet for about 4 minutes until softened.

Add minced garlic and cook for 1 minute, then mix in Italian seasoning, red pepper flakes, salt, and pepper.

Stir in the browned ground beef, then pour in half-and-half or milk, mixing until evenly coated and simmering briefly.

Combine the cooked shell pasta with the sauce mixture, tossing gently and cook on low heat for 2-3 minutes.

Optionally, stir in butter, and serve warm topped with grated cheese.