I have to make some cup cakes on Thursday for the school fete that is on Sunday.
If I ice them will the icing still be ok on Sunday?
This is the icing I was thinking of using

150g softened unsalted butter
500g icing sugar, sifted
1/3 cup passionfruit pulp
Yellow food colouring
1 tbsp milk

combine butter and icing sugar and beat until smooth. Add remaining ingredients and mix well.
Should I swap it for a lighter glaze without the milk etc?
How do I make such a thing?

And while I have your attention.... are passionfruit cup cakes the right choice for the cake stall? I could make berry and ricotta muffins instead (but I don't know how well they keep). Or a chocolate cake. I'm making some brownies so I don't want to go too OTT with the chocolate.