The class recipe for Aperol spritz is 3 parts Prosecco, 2 parts Aperol and 1 part soda water.
However, I find this often doesn’t have enough Aperol flavour, coupled with the ice melting and watering down the flavour even further. I also find myself topping up the volume with soda water, so this recipe is (in my opinion) the perfect ratio of flavour and volume. Experiment to find your preferred ratio of ingredients!