Place a large, heavy pot over medium heat and toss in the ground beef and the garlic. Stir, crumbling the meat with the spoon, until no trace of pink remains. 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 to the pot. Stir everything together really well, cover the pot, and reduce the heat to low. Gently simmer for 1 hour, stirring occasionally. Take an occasional peek and if the liquid level seems to be getting dangerously low, add up to a total of 1 cup water, a little at a time, to keep the chili from burning.
After an hour, stir in the beans. In a small bowl, use a fork to combine the masa harina with 1/2 cup water until it’s smooth. Pour some or all of the masa mixture into the chili, depending on how thick and gritty you prefer things. Stir together and then taste the chili and adjust the seasonings accordingly. Let the chili gently simmer until thickened and warmed through, about 10 minutes more.
Turn off the heat and ladle into bowls. Top with cheese and chives, if using, and serve with cornbread on the side, if desired.
To freeze the chili, let the chili cool to room temperature. Fill large or small resealable plastic freezer bags and freeze them flat for easy stacking.
To reheat the chili, remove individual bags of chili and place them in the fridge to thaw for at least 24 hours, then reheat in a saucepan over medium-low heat, adding 1/4 cup water if necessary to achieve the desired consistency OR place a bag of frozen chili on a microwave-safe plate and defrost it in the microwave according to the manufacturer's instructions and then transfer the nuked chili to a bowl and place it back in the microwave until warm. Place a bag of frozen chili in a microwave-safe bowl and reheat according to the manufacturer's instructions.