Some good ideas might be to puchase pre-made chocolat shells, or cups, make a frozen filling for them that can be stored in tubs, and fill just before serving. Of course you will need someone to fill them as they are served. Sounds like a job for a bridesmaid, or best man to me. You could fill the cups with frozen pudding, or just plain pudding, or with fruit sorbets, or even ice-cream. You could also fill them with a cheesecake filling that had been prefiously made, and just scooped out of a bowl and into the cups.
This could also be done with pre-made phylo dough cups.
Then theres always frozen bananas, or frozen strawberries, dipped in chocolate shell syrup.
Seeeeeya; Goodweed of the North