Combine butter, powdered sugar and peppermint extract in large bowl. Beat at medium speed, scraping bowl often, until creamy. In a separate bowl, combine flour and cornstarch.

Gradually add to creamed mixture and beat at low speed until well mixed.

Cover and refrigerate until firm at least one hour.

Preheat oven to 350°.

Shape dough into 1-inch balls, and place it 2 inch apart on ungreased baking sheets.

Bake at 350° for 10-12 minutes or until bottoms are lightly browned. Remove to wire racks to cool completely.

In a small bowl, beat butter until fluffy. Add the powdered sugar, milk and peppermint extract and beat until smooth.

Spread over cooled cookies and immediately sprinkle with crushed candies.

Store in an airtight container.