Place silicone molds on a baking sheet. Set aside.

In a large bowl, combine chocolate chips and broken bittersweet chocolate. Set aside.

In a saucepan, heat sweetened condensed milk and heavy cream until about 130°F, about 3-4 minutes.

Pour hot milk mixture over chocolates. Let sit for 3-4 minutes, then whisk until smooth.

Transfer chocolate to piping bag and pipe into molds about ¾ full. Top with mini marshmallows and insert stick.

Chill in refrigerator for at least 3 hours or overnight until firm.

Remove squares from molds and store until ready to serve.

To serve, place two squares in a mug, heat 2 cups of milk to 2.5 minutes in microwave, pour over squares, stir to melt and enjoy.