Using sorbet instead of ice cream in these sandwiches cuts back on fat to be truly good to your loved ones.
In a small bowl, whisk flour, cocoa powder, and pinch of salt. In a large bowl, using an electric mixer, beat butter and sugar on high until light and fluffy, 3 minutes. Add egg and vanilla; beat until combined. With mixer on low, gradually add flour mixture and beat until combined. Form dough into a disk, wrap in plastic, and refrigerate until firm, 1 hour.
Preheat oven to 350 degrees, with racks in upper and lower thirds. Roll out dough between lightly floured parchment paper to 1/8-inch thickness. With a 3-inch heart-shaped cookie cutter, cut out 18 hearts, rerolling scraps once. Place cookies, 1 inch apart, on two parchment-lined baking sheets. Freeze until cookies are firm, 10 minutes. Bake until edges are crisp, 12 to 14 minutes, rotating sheets halfway through. Let cool completely on sheets on wire racks.
Scoop scant 1/4 cup sorbet onto flat sides of 9 cookies; sandwich with remaining cookies. Wrap in parchment or waxed paper and freeze until firm, 20 minutes (or up to 1 week).