Preheat the oven to 450°F and line a baking sheet with parchment paper.
In a large bowl, mix together the flour, baking powder, sugar, salt and garlic powder.
Whisk the melted butter with the cold buttermilk until combined. The butter will solidify into small clumps – this is what we want!
Pour the buttermilk mixture into the dry ingredients, stirring just until incorporated.
Gently fold in the Parmesan and rosemary, being careful not to overmix.
Drop heaping spoonfuls of dough onto the prepared baking sheet.
Bake for 12-14 minutes, or until the biscuits are golden brown on top.