Use cheese grater to shred cold, unsalted butter. Place back in refrigerator.

Combine flour, sugar, salt, baking powder, and cream of tartar in a large bowl.

Using cutter, cut butter into dry mixture until there are pea-sized pieces of butter throughout.

Add milk and egg. Mix until just combined; dough should be sticky.

Place dough on floured surface and sprinkle flour on top. Knead 10-15 times.

Pat dough out until 3/4-1 inch thick. Cut biscuits using glass or round cookie cutter.

Place on cookie sheet with parchment paper. Brush tops with melted butter. Bake 10-15 minutes at 450.