Then simply thaw and assemble the day of the party. In large bowl, combine flour, baking powder, and salt. With pastry blender or 2 knives used scissor fashion, cut in butter until mixture resembles fine particles. Add milk and stir just enough to moisten flour. Bake 10 to 12 minutes, or until golden.
Transfer biscuits to wire racks to cool.
Spread inside of 1 half with a little mustard. Place ham slice on bottom half of biscuit and place top of biscuit on ham to make a little sandwich.