Step 1

Microwave butter and chocolate in large microwaveable bowl on HIGH 2 min. or until butter is melted. Stir until chocolate is completely melted and mixture is well blended. Add sugar; mix well. Blend in eggs and vanilla. Stir in flour.

Step 2

Refrigerate 1 hour.

Step 3

Heat oven to 350°F. Roll dough into 64 (1-inch) balls; place, 2 inches apart, on parchment-covered baking sheets.

Step 4

Bake 10 min. or just until centers of cookies are set. (Do not overbake.) Cool on baking sheets 1 min. Gently press 1 pretzel into top of each cookie; cool additional 5 min. Transfer to wire racks; cool completely.