Melt chocolate chips in a double boiler or in the microwave until just melted.
Pour a heaping tablespoon of melted chocolate into 6 cavities of the silcone mold.
Use a spoon to spread the chocolate out so it coats the entire cavity.
Tap the molds on the counter and set them aside for 10 minutes.
Spread any extra chocolate that has pooled in the bottom on the sides. Place in fridge for 30 minutes to harden.
Fill 3 of the cavities with cocoa and mini marshmallows.
Microwave a plate until warm.
To combine the spheres, gently press the edge of the other side of the sphere on the hot plate until the chocolate is slightly soft.
Press the two sides of the sphere together. Run your finger around the outside to seal.