How to Make It
Preheat the oven to 350°. In a large bowl, beat the eggs. Beat in the milk, grated Parmigiano-Reggiano cheese, parsley and basil. Season with salt and pepper.
In an 8-inch nonstick ovenproof skillet, heat the olive oil. Add the shallots and cook over moderate heat until softened, about 7 minutes. Add the tomato and prosciutto and cook, stirring, until warm, about 2 minutes. Pour in the eggs and cook until beginning to set on the bottom, about 3 minutes. Poke the mozzarella cubes into the eggs. Transfer the skillet to the oven and bake the frittata for about 20 minutes, until just firm when lightly pressed.
Set the skillet over high heat and shake the frittata until it releases, about 10 seconds. Place a large, flat plate over the skillet and carefully invert the frittata onto it. Let cool for 5 minutes, then cut into wedges and serve.