Cut dough in half; roll out both halves to an even 1/4-inch thickness.
Cut out cookies with a round 1-inch cookie cutter, rerolling scraps to get 72 cookies.
Coat 2 cookie sheets with cooking spray; place cookies on sheets 1 inch apart and bake 1 batch at a time until firm, 3 to 5 minutes.
Cool on wire racks.
Simmer chocolate chips and half-and-half in a small saucepan over low heat, stirring once or twice, until chocolate melts and is smooth, 1 to 2 minutes; remove from heat.
Let cool 1 minute.
Spread 1/2 teaspoon chocolate ganache on a cookie; press a second cookie on top to form a sandwich.