In the bowl of your mixer, combine butter, sugar, and vanilla until creamy.

Add flour, cocoa powder and salt and beat until the dough begins to come together.

Divide dough in half.

Shape each half into 6x2-inch round log.

Wrap each log in plastic food wrap and refrigerate at least 2 hours.

Heat oven to 350 degrees and line 2 cookie sheets with parchment paper.

Cut logs into ¼-inch slices with sharp knife.

Place 1 inch apart onto cookie sheets.

Bake 7-9 minutes or until lightly browned on edges. Let stand 5 minutes before removing from cookie sheets.

In small microwavable bowl, microwave chocolate chips and butter uncovered on High 1 to 1 ½ minutes or until melted; stir until smooth.

Dip half of each cooled cookie into melted chocolate and sprinkle with crushed peppermint pieces.

Place on waxed paper until chocolate is set.