Preheat oven to 375°F and grease a 12-cup muffin tin.
Cook ground beef in skillet until browned, then add onions and cook 2–3 minutes. Drain grease.
Stir in ketchup, mustard, garlic powder, salt, and pepper. Let mixture cool slightly.
Flatten biscuit dough pieces into 4-inch circles and press into muffin cups.
Spoon 2 tablespoons of beef mixture into each dough cup and top with cheese.
Add optional toppings such as bacon or pickles.
Bake for 15–18 minutes until golden brown and cheese is melted.
Let cool 3–4 minutes before removing from the pan.
Serve warm and enjoy your cheeseburger cups!