Melt chocolate wafers and use chocolate to coat the inside of molds. Use a spoon to spread the chocolate up the sides of the mold slowly, so it sets as you spread.
Put mold in freezer for 15 minutes to harden the chocolate.
If needed, add another layer of chocolate and freeze again to ensure that your chocolate bombs are sturdy.
Remove the chocolate from the mold and place half of the half-circles on a plate -- open side facing up like a bowl. Fill each with a serving of hot cocoa powder, a few chocolate chips, and marshmallows.
Heat a pan on stove (with a little water in it so it doesn't scorch). Press the top half of the mold onto the hot pan so that it melts the edges and you can press it onto the bottom half of the bombs.
Hold in place until the two halves seal and set.
Drizzle the top of the bombs with white chocolate and sprinkles.
To serve, place the bomb in the bottom of an empty mug and pour hot milk on top. The chocolate bombs will "explode" and all the goodies will fill the mug. Stir to mix.
Nutrition values are an estimate only; nutrition facts are for chocolate bombs only (not milk).