In a small mixing bowl, cream butter and powdered sugar until light and fluffy. Beat in lemon peel.
Combine flour and cornstarch; gradually add to creamed mixture and mix well.
Cover and refrigerate for 1 hour or until easy to handle.
Shape into 1-3/4 inch diameter roll; roll in non-pareils. Wrap in plastic wrap and refrigerate for 2-3 hours or until firm.
Preheat oven to 375 degrees. Unwrap and cut into 1/4 inch slices. Place 1 inch apart on ungreased baking sheet. Bake at 375 degrees for 9-11 minutes or until set and edges are lightly browned. Cool 1 minute before removing to wire racks.
In a small bowl, combine icing ingredients; spread over cookies.