Heat the oven to 425°F and line a large baking sheet with parchment. Whisk flour, baking powder, sugar, salt and garlic powder in a bowl.
Cut in the cold butter with a pastry blender or fingertips until the mixture has coarse crumbs and a few pea-size pieces. Fold in cheddar.
Pour in buttermilk and stir just until no loose flour remains; keep the dough rough rather than beating it smooth.
Drop 12 mounds onto the sheet with a large spoon, leaving 2 inches between them. Bake for 15 to 18 minutes until the tops and bottoms are golden.
Brush lightly with the melted tablespoon butter and let stand for 5 minutes before serving.