Tall and Fluffy Buttermilk Biscuits

2 cups unbleached flour 1 tablespoon double-acting baking powder 1 tablespoon sugar 1 teaspoon salt ½ teaspoon baking soda 4 tablespoons col butter cut in ¼-inch cubes 1½ cups cold buttermilk, preferably low-fat

Adjust oven to middle rack and heat oven to 500 degrees. Spray bottom of 9 inch cake pan with non-stick set aside. In processor pulse flour baking powder, sugar, salt and baking soda to combine. Scatter cubes over dry ingredients and pulse until resembles pebbly course cornmeal, 8 to 10 1 second pulses. Transfer dry ingredients to medium bowl add buttermilk and stir until incorporated (will be very wet and slightly lumpy. Using ¼ cup measuring cup sprayed with non-stick spray, scoop and roll in flour and place in pan forming 12 even sized rounds. Brush with hot melted butter. Bake 5 minutes and reduce oven temperature to 450 and bake until golden brown, about 15 minutes. Cool in pan 2 minutes invert from pan onto clean kitchen towel, turn biscuit right side upend break apart