1. Preheat oven to 375° and line a large baking sheet with parchment paper. Spoon about a tablespoon of cheese a few inches apart. Bake until bubbly and edges are beginning to turn golden, about 6 minutes. Let cool on baking sheet for a minute.
2. Meanwhile, grease bottom of a muffin tin with cooking spray, then carefully pick up melted cheese slices and place on bottom of muffin tin. Let cool 10 minutes.
3. In a large skillet over medium heat, heat olive oil. Add onion and cook, stirring occasionally, until soft, about 5 minutes. Stir in garlic then add ground beef, breaking up the meat with a wooden spoon. Cook until beef is no longer pink, about 6 minutes, then drain fat. Season with chili powder, cumin, paprika, salt, and pepper.
4. Transfer cheese cups to a serving platter.