This is what I did with the rest of my batch of Caramelized Fennel and Onions, after using some on pizza a few days ago. Goat cheese goes beautifully with these flavors (it would make a nice variation for the pizza, too). Like many frittatas, this works for any meal of the day. Can be served hot or at room temperature.
6 eggs, beaten
1 - 1 1/2 cups Caramelized Fennel and Onions
3-4 oz. crumbled goat cheese
Salt and pepper to taste
1 medium tomatoes, sliced 1/8-inch thick (seeds removed)
Combine the eggs, caramelized onion and fennel, goat cheese, and salt and pepper in a medium bowl. Let it sit at room temperature for 30 minutes or so if you can.
Oil well a 10-inch oven proof skillet and heat it up over medium heat. Pour in the egg mixture and make sure the veggies and cheese are evenly distributed. Cook, without stirring, over low-medium heat until the eggs are largely set. While you do so, preheat the broiler. Lay the tomato slices on top of the egg mixture. Finish the friittata under the broiler for 3-5 minutes, until the eggs are cooked through.