Preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper.

In a large mixing bowl, whisk together the flour, baking powder, sugar, salt, garlic powder, and onion powder until well combined.

Add the cold, cubed butter to the dry ingredients. Using a pastry cutter, two knives, or your fingertips, cut the butter into the flour mixture until it resembles coarse crumbs with some pea-sized pieces of butter remaining.

Stir in the shredded cheddar cheese until evenly distributed.

In a separate small bowl, whisk together the cold buttermilk and cold milk. Gradually pour the liquid mixture into the dry ingredients, mixing with a fork until just combined. Be careful not to overmix; the dough will be shaggy.

Turn the dough out onto a lightly floured surface. Gently knead 3-4 times, just enough to bring the dough together. Do not overwork.

Pat the dough into a roughly 1-inch thick circle or rectangle. Using a 2.5 to 3-inch biscuit cutter (or a knife to cut squares), cut out 12 biscuits. Reroll scraps gently if necessary to get all biscuits.

Place the biscuits about 1 inch apart on the prepared baking sheet.

Bake for 12-15 minutes, or until the tops are golden brown and the biscuits are cooked through.

While the biscuits are baking, melt the 1/2 cup butter in a medium mixing bowl. Stir in the minced garlic (or garlic powder), dried parsley flakes, and optional cayenne pepper.

As soon as the biscuits come out of the oven, generously brush the warm garlic butter topping over each biscuit. Serve immediately.