• Fast
• Make-Ahead

Ingredients

1. 1 dozen large eggs
2. 2 tablespoons water
3. Salt and freshly ground pepper
4. 1 packed cup shredded Gruyère
5. 4 ounces prosciutto, sliced 1/4 inch thick and cut into 1/4-inch dice
6. 1/4 cup extra-virgin olive oil
7. 1 pound Yukon Gold potatoes, peeled and cut into 1/2-inch dice
8. 2 scallions, thinly sliced

Directions

1. Preheat the oven to 375°. In a bowl, beat the eggs with the water and season with 3/4 teaspoon of salt and 1/2 teaspoon of pepper. Beat in the Gruyère and prosciutto.
2. Heat the olive oil in a large, nonstick ovenproof skillet. Add the potatoes and cook over moderately high heat, stirring occasionally, until tender and golden brown, about 7 minutes. Add the scallions and cook for 1 minute. Stir the egg mixture and add to the skillet. Stir to distribute the potatoes. Cook until the bottom is just set, about 3 minutes; lift the frittata to allow the uncooked eggs to seep underneath.
3. Bake the frittata for about 10 minutes, until nearly set in the center.
4. Preheat the broiler. Broil the frittata 8 inches from the heat for 1 minute, until the top is just beginning to brown. Cut the frittata into wedges and serve hot or at room temperature.

Make Ahead

The unmolded frittata can be kept at room temperature for 4 hours.