1. Preheat oven to 425 degrees.
2. In a large skillet, cook ground beef.
3. Spray muffin tins with cooking spray.
4. Heat a nonstick skillet over medium heat.
5. Working with one tortilla at a time, place in skillet, over medium heat. Heat for 20-30 seconds per side. Flip and warm both sides.
6. Place warm tortilla into muffin tin holes. Repeat with all 12 tortillas.
7. Spray tops lightly with cooking spray. Bake for 5 minutes or until lightly browned. Remove from oven and fill each shell with 1 tablespoon refried beans and 2 tablespoons beef. Top with any or all of your favorite toppings.