Big-batch frittata is deceptively easy when you make it in a rimmed baking sheet. Using the oven means that the eggs cook slowly and evenly, for a custardy (not rubbery) frittata. This one packs in leafy spinach, salty salami, and tiny mozzarella balls, aka bocconcini. Once that bakes up in a 400º F oven, serve it with other classic antipasti ingredients like sundried tomatoes, artichoke hearts, and focaccia. Serve any extra frittata for breakfast on top of the extra toasted focaccia.