Heat oven to 350°F. Spray bottom of 13x9-inch pan with cooking spray. In medium bowl, stir together softened butter and egg. Stir in cookie mix until soft dough forms. Press mixture in bottom of pan, using floured fingers.
Bake 19 to 21 minutes or until golden brown. Cool 30 minutes.
In medium saucepan, melt butter. Add sugar, milk, chocolate chips and vanilla. Continue to whisk until chocolate is completely melted and mixture is smooth. Allow to cool slightly and then spread over cooled cookie.
Cool completely, about 30 minutes. Once cooled, using frosting with a tip or a gel pack to decorate. Top with your favorite candy.
For bars, cut into 7 rows by 5 rows.
by The Savvy Kitchen