Preheat oven to 350 degrees Fahrenheit and grease a 9″ x 12″ baking dish with a little nonstick cooking spray. Sit aside.
Bring a large pot of salted water to a boil and cook the pasta for 2 minutes less than the package directions indicate. drain well.
Meanwhile, in a large, heavy-bottomed saucepan, cook ground beef and onion over medium heat until beef has browned, about 8 minutes. Add garlic and cook for another 2 minutes.
Add tomatoes, tomatoes, chili peppers, chili powder, and cumin. Season liberally with salt and pepper.
Add the drained pasta, as well as the sour cream and 1 1/2 cups of the cheese. Stir until smooth. Transfer to a prepared baking dish and top with the remaining cheese.
Bake until bubbles and cheese melt, about 20 minutes. Leave it for 5 minutes before serving.
Enjoy!