Preheat your oven to 450°F.

In a medium mixing bowl, combine the Bisquick baking mix and baking powder using a whisk.

Grate 4 tablespoons of cold butter into small shreds. Add the shreds to the Bisquick mixture and use a pastry blender or two forks to mix until the butter is the size of small peas.

Stir in the milk with a wooden spoon until the dough comes together, but be careful not to overwork it.

Put the remaining 2 tablespoons of butter in a cast iron skillet and place it in the oven to melt while you prepare the biscuits.

Lightly sprinkle flour or extra Bisquick mix on a work surface. Turn the dough out onto it and gently fold it onto itself three times. Press the dough to about 1 inch thick.

Use a 2-inch biscuit cutter to cut out biscuit rounds. Press the scraps of dough together, roll them out again, and cut additional biscuits.

Remove the hot skillet from the oven and swirl the melted butter to coat the bottom.

Place the biscuits into the skillet and bake for 14-16 minutes, or until the tops are golden brown.

Serve warm.