Melt the chocolate to package instruction and then use a spatula to evenly spread it in the mold, being sure to have the chocolate goes into each corner of the mold.
Set the tray into the freezer for about 10 minutes.
Remove from the freezer and add a little more chocolate around all of the edges of the molds to reinforce them. Fill in any thin areas at the same time. Allow this new layer to harden for a few minutes in the freezer again.
While these are chilling again, warm a plate so that you can melt the edges of
the HCB and seal the two sides together.
Remove from the freezer and carefully take each egg half out of the mold, set onto a cold plate while you remove them.
One at a time, melt the edges of the eggs on the hot plate so they are smooth and return to the cold plate.
Fill half of the chocolate eggs with marshmallows.
Then melt the edges again of the other empty eggs and press onto the halves with the marshmallows.
Melt the white chocolate and reheat the dark chocolate if needed. Drizzle the white chocolate first, followed by the dark chocolate, this can be done with a fork or piping bag. Immediately top with the sprinkles.
These will store nicely in an airtight container in the fridge for about two weeks so feel free to make them ahead of time.