In a large stock/soup pot, brown beef, and drain fat. Return beef to pan and add pinto beans, tomato sauce, taco seasoning, brown sugar, and sour cream. Stir and keep warm.

In a separate pot, boil elbow macaroni noodles according to directions on package.

Meanwhile, in a medium saucepan, melt butter. Add flour and cook 1 minute. Pour in milk while whisking constantly. Bring to a boil and add shredded cheese. Stir until melted.

Drain noodles and add to pot with chili. Add cheese to pot with chili. Stir and season additionally with salt and pepper, if needed. Serve hot.