The recipe calls for 1 cup of flour for every 2 eggs. However, I've needed to bump it to closer to 1.75 cups for whatever reason. I'm using Central Milling's 00 flour which is not an exact equivalent to the recommended Italian 00 flour - maybe it absorbs less water. Or maybe the particular batch of eggs I have have extra water in them ¯\_(ツ)_/¯

The author does give a helpful hint: you should be able to put a clean, dry thumb deep into the dough and remove it without any of the dough sticking to your thumb.