Preheat the broiler.
Brown the franks in a small skillet over medium heat. Lightly toast the buns under the broiler. Put the franks on the buns and spoon on a bunch of chili. Add the cheese all over the top, then heat in the microwave to melt the cheese, 25 to 35 seconds. (Or if you're using an ovensafe plate, place it under a low broiler until the cheese melts, about 1 minute.) Sprinkle with the onion and dive in.
In a large, heavy pot, brown the ground beef with the garlic over medium heat until the beef is totally cooked, 8 to 10 minutes. Drain off most of the excess fat, leaving a little behind for moisture and flavor. Add the tomato sauce, tomato paste, chili powder, cumin, oregano, salt and cayenne. Stir together well, cover the pot and reduce the heat to low. Simmer for 1 hour, stirring occasionally; if the liquid level seems low, add up to 1 cup water to keep it from burning.
After an hour, stir in the kidney and pinto beans. In a small bowl, combine the masa harina with 1/2 cup water and stir together with a fork until it's smooth. Pour the masa mixture into the chili. Stir together well, then taste the chili and adjust the seasonings. Simmer the chili for another 10 minutes to thicken, then turn off the heat and let it cool.
Fill freezer bags with 2-cup portions and freeze them flat for easy stacking (or freeze in other freezer-safe containers).