Callaloo Frittata

Preheat oven to 350°F.

Bring a small pot of water to a boil. Peel potatoes and cut into 1/2-inch pieces. Add the potatoes to the boiling water and cook until tender, about 7 minutes. Drain; set aside.

Whisk eggs in a medium bowl. Add milk, feta and salt; whisk to combine.

Heat oil in a well-seasoned 10-inch cast-iron skillet over medium-low heat. Add onion; cook, stirring constantly, until softened, about 1 minute. Add greens; cook, stirring, until wilted, 2 to 3 minutes. Add the potatoes; cook, stirring frequently, until the potatoes are dry, about 1 minute. Pour in the egg mixture; mix until the greens and potatoes are evenly distributed. Cook, undisturbed, for 5 minutes.

Transfer the skillet to the oven and bake until the middle is just set, 15 to 20 minutes.

Season the frittata with cracked pepper, if desired. Slice into 4 pieces and serve with toast.