Heat the butter in a 10-inch skillet over medium heat. Add the onion and garlic and cook until tender. Remove the onion mixture from the skillet.
Cook the beef in the skillet over medium-high heat until well browned, stirring often to separate meat. Pour off any fat.
Stir the onion mixture, taco seasoning, soup, sour cream and picante sauce in the skillet and cook until the mixture is hot and bubbling, stirring often. Serve the beef mixture over the noodles.