A frittata is basically an open-faced omelet. The number of variations is limited only by your imagination. A frittata can be served either hot, warm, or cold and is delicious in a sandwich. It is easier to make than an omelet because it does not require folding. The āfillingā is mixed with the eggs before cooking, and the mixture is poured into an ovenproof nonstick skillet in which some butter has been heated. Once the bottom of the frittata browns well and only the top is runny, the skillet is placed under the broiler for 2 to 3 minutes until the top is golden brown and the frittata is done. For the recipes that follow, a 10-inch skillet is the perfect size, making a ½-inch-thick frittata which serves 4 as an appetizer or more as part of a buffet.