1. In bowl, combine flour and cocoa. In large bowl, with mixer on high, beat butter and sugar until fluffy. Beat in eggs and vanilla until well blended. Reduce mixer to low, and beat in flour mixture. Divide dough in half. Wrap and refrigerate 1 hour.
2. Line 9 x 13-inch baking pan with plastic wrap. Smooth ice cream evenly into pan, and freeze 1 hour.
3. Heat oven to 375 degrees F. On floured surface, roll dough out to 1/4-inch thickness. Using a 2-1/2-inch heart-shaped cookie cutter, cut out hearts, then transfer to baking sheet, 1 inch apart. With tines of fork, prick the tops of the cookies. Bake 12 minutes. Cool 2 minutes and transfer to wire racks. Cool completely.
4. Using same cookie cutter, cut out heart-shaped portions of ice cream. Sandwich between two cookies, and place in freezer until ready to serve.