Preheat oven to 450 degrees F. Line a baking sheet with parchment paper.

In a large bowl, mix the dry ingredients. Grate the frozen butter into the flour and, using a fork, coat the butter with the flour. Add the buttermilk and mix until almost all of the flour in incorporated (do not mix too much or the biscuits will be dense).

Sprinkle flour on your countertop and scoop out the biscuit dough. Gently fold the dough until it becomes more solid (roughly 20 times), only adding flour to prevent it sticking to your hands or countertop. Pat flat so the dough is at least 1/2 inch thick.

If you want circles, cut with any item that is at least 2 inches round (a biscuit cutter, a drinking glass, an empty food can, etc.). If you want squares, just cut with a knife. Place biscuits on the parchment-lined baking sheet an bake for 8 to 12 minutes (until the edges start to brown). Let cool a few minutes, then split with a fork (use the tines of a fork to split the biscuit instead of a knife). Serve.

Great Substitute
Substitute shortening or butter for the margarine.

Larger Biscuits
If using a 3-inch cookie cutter, you will be able to cut out 8 biscuits.
Bake as directed. Makes 8 servings, 1 biscuit each.

Crustier Biscuits
For a crustier biscuit, roll dough 1/4-inch-thickness; cut with 2-1/4-inch cutter. Continue as directed, increasing baking time to 12 minutes.

Makes about 8 servings, 3 biscuits each.