Place the cones in a cupcake pan (if they have a flat bottom they should stay standing, however if you're worried about moving the pan and having them fall you can scrunch up some foil and place them in each cup of the pan around the cone for extra support).
Fill each cone with batter about 1/3 to half full. Because most cones are skinnier on the bottom the cake should bake up to fill the top of the cone, but if you fill it too full the cake will bake over the sides of the cone (you can do a test cone first if you're worried about overflow).
Bake according to mix intstructions or recipe for cupcake times. Let cool.
Once the cupcakes are cool, you can start decorating. I filled a pastry bag with icing and I used a larger star tip to get the ice cream swirl effect, but you could use any size or shape tip you prefer. (You don't even have to use a pastry bag, you could just use a spatula to ice the cupcake cones. I just prefer the swirl look.)
On top of the icing, sprinkle on your favorite toppings. I just used colored sprinkles for half of mine and left the other half plain. But you really could use anything, whatever your favorite ice cream topping is, just sprinkle it on top of the icing (although, hot fudge might not work so well).
These are great for parties for any age because they are so fun and festive. Plus with these you don't have to worry about the hot summer day melting away your dessert (unless it's so hot the icing melts, but then you probably should find some shade and get out of the sun anyway).