Preheat the oven to 425°F.

Combine flour, salt, baking powder, and sugar in a large bowl.

Grate frozen butter and mix into dry ingredients until a crumb is formed.

Add cold milk and mix until the dough forms.

Turn out the dough onto a floured surface and work it into a 1-inch thick square.

Fold the dough evenly into thirds to form layers and roll it out to ¾ to 1-inch thickness.

Cut 2 ½-inch biscuits.

Turn the biscuit over and brush the flat side with milk to help them brown.

Place the biscuits with the flat, brushed side up on a baking sheet lined with parchment paper or a cast iron skillet.

Bake until the tops of the biscuits are browned, 15-18 minutes.

When the biscuits come out of the oven, use the remaining piece of frozen butter to rub across the top of the hot biscuits. Hold the butter on top of each biscuit and let it start to melt before rubbing.