In a mixing bowl, whisk eggs, milk, salt, and pepper. Set aside.
Heat olive oil in oven-safe skillet. 4. Sauté leeks until softened, about 5 minutes. 5. Add greens and cook until just wilted.
Pour egg mixture over vegetables in skillet. 7. Sprinkle cheese evenly over the top. 8. Transfer skillet to oven and bake 20–25 minutes, until center is set.
Cool slightly before slicing. Garnish with parsley or chives.