Preheat your oven to 350°F (175°C). Gather your ingredients and equipment.

In a large skillet, brown the lean ground beef for 6-8 minutes until fully cooked.

Melt 2 tablespoons of butter in the skillet, add diced onion and bell pepper, and sauté for about 4 minutes.

In a mixing bowl, combine sautéed vegetables, cooked beef, ketchup, Worcestershire sauce, salt, and pepper. Fold in half of the cheddar.

Stuff the cooked pasta shells with the cheesy beef mixture and arrange in a greased baking dish.

In the skillet, whisk together beef broth and milk, then add cornstarch until thickened. Stir in remaining cheddar.

Pour half of the cheese sauce over the stuffed shells and bake for about 10 minutes.

Let cool for a few minutes and serve with remaining cheese sauce on the side.