When should I add spinach to homemade pizza?
The moisture that you're talking about really has nothing to do with draining it or wringing it out. When it's heated, the cell structure breaks down and the water in the cells is released. Since it's predominately water, that means you have a lot of moisture on your pizza to make your crust soggy. At the restaurant I used to work at we had two methods. If there wasn't going to be a lot of spinach on the pizza, then we would just put it on raw. If there was going to be a lot of it, then we would give it a quick saute and then put it on the pizza. I would do the same thing with squash, eggplant, etc. Anything with a high moisture content. You could also roast it first. In both cases, I wouldn't cook it for long as the goal is to just get most of the water out and then let it finish on the pizza in the oven.