Mint-Filled Chocolate Thumbprints

Ingredients

• 0.5 cup granulated sugar 
• 1 cup butter softened
• 1 teaspoon vanilla 
• 1  egg yolk 
• 1.5 cups flour all-purpose
• 0.3 cup cocoa powder unsweetened
• 0.3 cup butter softened
• 1 cup powdered sugar 
• 1 tablespoon milk 
• 0.3 teaspoon peppermint extract 
• 2 drops drop natural food coloring green
• 0.3 cup semi chocolate chips 
• 0.3 teaspoon shortening 

Equipment

• bowl
• baking sheet
• oven
• wire rack
• hand mixer
• ziploc bags
• microwave

Directions

1. Heat oven to 375°F (if using dark or nonstick cookie sheet, heat oven to 350°F). In large bowl, beat granulated sugar, 1 cup butter and the vanilla with electric mixer on medium speed until fluffy. Beat in egg yolk until smooth. Beat in flour and cocoa.
2. Shape dough by rounded teaspoonfuls into 1-inch balls. On ungreased cookie sheet, place balls 1 inch apart. With index finger or thumb, make indentation in center of each ball.
3. Bake 7 to 9 minutes or until set. Immediately remove from cookie sheet to wire rack. Cool completely, about 30 minutes.
4. In small bowl, beat 1/4 cup butter and the powdered sugar on low speed until smooth. Beat in milk, peppermint extract and enough food color for desired color. Spoon about 1/2 teaspoon filling into each cookie.
5. Place chocolate chips and shortening in small resealable food-storage plastic bag; seal bag. Microwave on High about 1 minute or until softened. Gently squeeze bag until chocolate is smooth; cut off tiny corner of bag. Squeeze bag to drizzle chocolate over cookies.
6. Let stand about 1 hour or until chocolate is set.