Any tips for increasing the recipe?

Increase without any adjustments (i.e., multiple each ingredient quantity by the same amount) and leave extra time for chilling in the fridge - or divide it into two or three bowls to reduce the chilling time. I'd probably remove 1/3 of the chilled mixture from the fridge at a time when shaping, as one might expect it to be easier to roll the balls while the ganache is cold.