Preheat your oven to 425 degrees Fahrenheit and line two baking sheets with parchment paper.
Stir together the flour, baking powder, salt, pepper, and garlic powder in a large bowl. Cut in the butter using a pastry knife, your hands, or a food processor. Stir in the grated cheddar and chopped sage then stir in one-and-a-half cups of the buttermilk. Stir just until combined, adding more buttermilk if needed. The mixture should be pretty wet as these are drop biscuits as opposed to classic biscuits that require rolling.
Using a two-ounce disher/ice cream scoop, scoop eight biscuits onto each prepared baking sheet. Sprinkle the top of each biscuit with a little coarse salt, if using, and bake in the preheated oven for 25 to 30 minutes or until the biscuits are cooked through and golden brown.