PREHEAT oven to 400°F. Mix flour and baking powder; set aside. Beat butter in large bowl with electric mixer on medium speed until creamy. Gradually add sugar and 1 pkg. of the dry gelatin, beating until light and fluffy. Add egg and vanilla; mix well. Gradually add flour mixture, beating until well blended after each addition.

SHAPE dough into 1-inch balls. Place, 2 inches apart, on ungreased baking sheets. Flatten with bottom of clean glass. Sprinkle with remaining dry gelatin.

BAKE 8 to 10 min. or until edges are lightly browned. Remove from baking sheets to wire racks. Cool completely. Store in tightly covered container at room temperature.