8 large eggs (I used 1/2 egg whites)
1/4 cup milk (I used 2%)
4 ounces prosciutto di Parma
1 tablespoon butter
1 tablespoon olive oil
2 ounces Parmesan, grated
6 ounces feta cheese, crumbled (I used reduced fat)
For the Onions
Remove the shoot and base of the onions. Peel off the onion skin and cut the onions from top to bottom. Cut the onion into 1/4-inch slices. Add the olive oil to a large sauté pan over medium heat, then add the onions and season with the salt.
Cook until the onions begin to wilt, about 30 minutes, stirring every 15 minutes to prevent sticking. Reduce the heat to low and continue to stir every few minutes as the onions reduce in size.
Continue cooking until the onions are dark brown. Turn off the heat and scrape up any bits that are stuck to the bottom of the pan. Allow the onions to cool.
For the Frittata
Preheat the oven to 350 degrees F.
In a small bowl, add the eggs and milk and mix to combine.
Chop the prosciutto into 1/2-inch pieces.
Add the butter to an oven-safe pan over medium heat. Once the butter has melted, add the olive oil and reduce the heat to medium-low.
Pour the egg mixture into the pan. When the eggs start to set, add the Parmesan and prosciutto. Stir gently and sprinkle with the feta cheese.
Bake in the preheated oven until the frittata is set and the feta cheese is melted, about 15 minutes.
Remove from the oven and using a rubber spatula, loosen the frittata from the sides of the pan. Slide it onto a cutting board and cut into wedges. Top with onions before serving.
Replace the onions with sour cream and salsa.
Replace the prosciutto with bacon or another salty ham