Using a double boiler, melt your white chocolate until smooth.
When ready, line your hot chocolate bomb mold by dividing the chocolate into 4 shells. Spread around using the back of a spoon until smooth and fully covered.
Pop these in the freezer for 5-10 minutes until set.
Remove from freezer. Take one shell out of the mold and fill with 2 tbsp hot chocolate powder, 1 tbsp mini marshmallows and sprinkles. Repeat with remaining ingredients in another half shell.
Heat a small pan over the stove and when it is warm, place an empty shell on it to melt the edges a bit. Quickly place right on top of one of the filled shells and gently press to seal. You can smooth the edges with your fingers.
Pop in the freezer again until set.
Drizzle with a little extra chocolate and top with sprinkles if you'd like. And then, enjoy!
