so i posted a thread about getting cupcakes from my house to a familys party about 1/12 hours away from me and the responses were great and i have everything i need to get them there 

my issue is with my buttercream that i use its more of a softer consistancey and i was wondering if there was anything i could do to make it a little more stablized so that even with the ice packs on the boxes and all the cold air being on it that it will hold up its shape

i am making vanilla cupcakes filled with cookie dough and topping it with my marshmallow buttercream 

this is the recipe i use for a good amount of my cupcake flavors

2 sticks of  unsalted butter at room temp

7 oz jar of marshmallow creme or fluff

2-3 cups of powder sugar 

 a capfull  of madagascar burbon vanilla

cream butter then add fluff until combined

then slowly add in powder sugar until you get the consistancey that you like

pour in vanilla and mix 

i use this to pipe on my swirls but i find this buttercream to get soft if left in the heat so i have to work fast when i decorate and then fridge so it sets

does anyone know anything i can add to it to make it less soft and alittle more firm 

or does anyone have a really easy buttercream that would work better ( nothing using lard or crisco i prefer butter)