Poke a hole in the middle of the frittata with the tip of the spatula to check that the egg is set. When it's ready, slide the frittata onto a plate. Let it cool a bit, then slice into wedges and serve. ☞ TESTER TIP: A frittata tastes good hot, better after it has cooled for half an hour or so, and possibly best after it has had a chance to regroup on the countertop for an afternoon. Just sayin'.