Streamline the birthday party cake-and-ice-cream delivery by scooping the ice cream into single-serving portions ahead of time! The fantastic idea appeared in the comments of another muffin tin hack (Muffin tin as drink serving tray). Thank you, MaryG (and thanks to your sister for coming up with this idea in the first place)!
My sister used cupcake liners in a muffin tin to pre-portion ice cream to go with cake at her kids' birthday parties. Just portion out a scoop in each, and throw it into the freezer until time to serve. It makes chaotic cake time so much easier!
Tip: I would take the ice cream out of the freezer a few minutes before you serve it to let it soften up.
More: Hacks for birthday parties and other special occasions