PREHEAT oven to 375° F.
COMBINE flour and baking powder in small bowl. Beat butter, sugar and vanilla extract in large mixer bowl until creamy. Add eggs one at a time, beating well after each addition. Gradually beat in dry ingredients. Stir in morsels. Refrigerate for a few minutes until firm.
SHAPE dough into 3/4-inch balls; place three together to form shamrock shape on ungreased baking sheets. Roll small amount of dough to form stem. Sprinkle cookies with green sugar. Repeat with remaining dough.
BAKE for 8 to 10 minutes or until edges are lightly browned. Cool on baking sheets for 2 minutes; remove to wire racks to cool completely.
Makes about 4 dozen cookies.