Preheat oven to 350°F (175°C).

Brown the ground beef in a skillet over medium heat.

Drain off any excess grease from the browned ground beef.

Stir in the taco seasoning mix, tomato sauce, and chopped green pepper into the skillet with the ground beef.

Bring the mixture to a boil, then remove from heat.

In a separate bowl, combine the cooked and drained corkscrew macaroni, half of the shredded cheddar cheese (1/2 cup), and sour cream.

Transfer the macaroni mixture to the bottom of a 6 x 10-inch baking dish, spreading it evenly.

Pour the ground beef mixture over the macaroni layer in the baking dish.

Sprinkle the remaining shredded cheddar cheese (1/2 cup) evenly over the top of the meat mixture.

Bake in the preheated oven for 30 minutes, or until the cheese is melted and bubbly.

Let the casserole cool slightly before serving.