Cook ground beef, in batches, in a large skillet over medium-high heat about 5 minutes, stirring until it crumbles and is no longer pink. Drain well.
Add garlic, reduce heat to medium, and sauté 2 minutes until tender. Add 6 tablespoons chili powder and 1 tablespoon cumin, stirring to coat meat evenly. Add tomato sauce and 2 cups water. Bring to a boil; cover, reduce heat, and simmer 1 hour. Stir 1 tablespoon masa at a time into meat mixture; allowing chili to thicken between additions to desired consistency.
Cook, uncovered, 20 more minutes. Stir in salt, red pepper, and, if desired, paprika. Stir in remaining 1 tablespoon chili powder 5 minutes before serving, and garnish, if desired.