In a large bowl, combine the biscuit mix, drink mix and baking powder. Combine the egg, milk and sour cream; stir into dry ingredients just until moistened. Fold in chocolate chips. Pour batter by 1/4 cupfuls onto a greased hot griddle. Turn when bubbles form on top; cook until second side is golden brown. Serve with maple syrup and butter if desired. Cool remaining pancakes; arrange in a single layer on baking sheets. Freeze overnight or until frozen. Transfer to a resealable plastic freezer bag. May be frozen for up to 2 months. To use frozen pancakes: Place on a lightly greased baking sheet. Bake at 400° for 4-6 minutes or until heated through. Serve with maple syrup and butter if desired.