Combine flour, salt and baking powder in a large mixing bowl.
Add sour cream and stir to combine.
Add frozen grated butter and mix with a pastry blender until combined but do not overmix the dough.
Add buttermilk about a quarter of a cup at a time stirring until well blended.
Place biscuit dough on a well-floured surface.
Knead about 30 seconds working in flour until dough is not sticky.
Fold dough into thirds, then roll dough out with a rolling pin until about 1 ½ to 2 inches in depth.
Cut biscuits with a biscuit cutter and place on greased cookie sheets.
Place scrap pieces of dough together and form another round dough with your hands.
(This will yield about 3 more biscuits).
Place on prepared cookie sheet.
Bake biscuits at 450° about 12-15 minutes or until lightly golden brown.
Melt butter.
Brush melted butter over top of biscuits.