Combine flour, baking powder and salt in a large mixing bowl. Using a pastry blender or 2 knives, cut butter into flour. (you want butter to be the size of peas.)
Stir in buttermilk, starting with 3/4 cup, just until dry ingredients are wet. Do not overmix. Add more buttermilk if needed.
Sprinkle 1/2 of cinnamon sugar evenly over top of biscuit dough. Fold dough over one time. Using a large spoon or large cookie scoop, place dough, 2 inches apart, on a lightly greased baking sheet.
Brush tops of biscuits with melted butter then generously sprinkle remaining cinnamon sugar on tops of biscuits.
Bake in a preheated 450 degree oven for 13-15 minutes, until golden brown.
