Line the baking sheet with aluminum foil for easy cleanup. Watch the little ones—the center of the marshmallow will still be warm after the 5-minute cooling time. Chocolate kisses will soften but not melt.
Place crackers on baking sheet. Top each with 1 milk chocolate kiss and 1 marshmallow half, cut side down.
Bake at 350° for 8 minutes or just until marshmallows begin to melt. Let cool on a wire rack 5 minutes.