Cook the elbow macaroni according to package directions.
In a large non-stick skillet, heat 1 tablespoon olive oil over medium heat. Add the onion and cook for about 5 minutes, until tender. Add in the garlic and cook for a minute longer.
Stir in the ground beef, chili powder, salt and black pepper and cook until the meat has browned. Drain any excess fat from the pan.
Sprinkle 2 tablespoons flour over the meat and cook for a minute or two.
Add in the tomatoes and simmer on low. The sauce will start to thicken a bit as it cooks.
To the meat mixture add in the cooked and drained macaroni, 1/2 cup sour cream, 2 tablespoons milk and 2 cups shredded sharp cheddar cheese.
Pour the mixture into a large casserole dish. Top with remaining cheese and sprinkle 1/2 cup panko bread crumbs on top.
Bake for about 20-25 minutes, or until the cheese is melted and bubbly.
Sprinkle the casserole with chopped fresh parsley before serving. Enjoy!