1. Combine piecrust mix, the 3/4 cup sugar, 2 tablespoons instant coffee powder and baking powder in medium-size bowl; stir in egg and vanilla, mixing well to form a very stiff dough. (If dough seems dry and crumbly, knead a few times until smooth.)
2. Shape into a roll about 9-inches long on wax paper; wrap and chill until very firm.
3. Unwrap roll; slice into thin rounds with sharp knife. Place, 1 inch apart, on cookie, sheets.
4. Mix the 1 tablespoon instant coffee powder and sugar in cup; sprinkle evenly over cookies.
5. Bake in.hot oven (400°) 8 minutes, or until very lightly browned around edge. Remove from cookie sheets with spatula; cool on wire racks.