Silicone molds work better than paper liners while trying to make the chocolate shells, as they peel off easily. If using paper muffin liners, I would suggest that you make a cut (tear) on one edge of the liner cup, before coating it with chocolate. This way, when the cups are frozen, you can start peeling off the liner from the torn area, its easier to peel it off.
You can use any kind of filling that you like. Some suggestions would be peanut butter, white chocolate mousse, ice cream, flavored cream -cheese, pudding, custard, ganache, or even flavored yogurt.
Pair it with other seasonal fruits like peaches, cherries, berries, oranges, etc
Top each cup with some whipped cream for extra points on the presentation.