Get the lined mini-muffin pan and the melted chocolate. Using a spoon, ladle some of the melted chocolate into each liner. You don't have to be precise about how much chocolate you're putting into the liner at this point — it should be about a tablespoon, enough to cover the bottom of the cup by 1/4" or so.
Once all the cup bottoms have chocolate, place a filling disc into each one, slightly pressing down so that it squeezes some of the melted chocolate upward. The disc should show a thin moat of chocolate all around — it should not touch the sides of the cup.
When the pan is filled with the discs, ladle a little more melted chocolate over each one so that the filling is just covered. Smooth over each one with the back of a small spoon.
After all the cups are completely assembled, chill in the freezer for about 10 minutes until hard. If you're reusing the pan, you can pop the cups out and keep them chilled in the refrigerator (not freezer) until it's time to bring them to the party, and immediately re-line and reuse the pan.