Preheat the oven to 375°F.

Whisk eggs, milk, salt and pepper together until smooth.

Heat olive oil in a 10-inch oven-safe skillet over medium heat and cook the leek 4 minutes, until soft.

Add the peas and cook 2 minutes more, just until bright green.

Pour the egg mixture evenly over the vegetables in the skillet.

Scatter the feta cheese over the top.

Cook undisturbed on the stovetop 3 minutes, until the edges begin to set.

Transfer to the oven and bake 12 to 15 minutes, until the center is just set and no longer wobbles when the pan is gently shaken.

Scatter mint and chives over the top, slice into wedges and serve warm or at room temperature.