Bake your cake according to package instructions. Once baked, crumble with your hands into small crumbs.
Mix cake and frosting together until well combined. Place in either a 9x13 or 9x9 baking dish that you've previously sprayed with non-stick spray or lined with parchment paper.
Chill mixture for 1-2 hours.
Cut circles out of the mixture using a circle cookie or biscuit cutter and place circles on parchment paper.
Cut 1/8 off the end of each marshmallow then press the sticky side onto one of the circles to create a Mickey Mouse ear. Repeat on the other side with a second marshmallow. Repeat with all of the circles.
Melt white chocolate in microwave in 30 second increments until completely smooth. Stir.
Pour white chocolate over Mickey Mouse heads until completely covered. Top with sprinkles and place in refrigerator or freezer until chocolate hardens.
Cut the excess chocolate off carefully until you have the correct shape then turn over and coat the back side with white chocolate anywhere that wasn't originally coated. Let chill again.
Poke a cake pop stick gently into the bottom of the cake pop, making sure not to go further than about 3/4 of the way up through the head or the cake pop will fall down the stick.