Step 1

Preheat the oven to 425º F.

Step 2

Crack the eggs into a medium mixing bowl. Add the milk and the salt. Whisk until the egg yolks and whites are well blended. Add the cheese, and give the mixture a quick whisk to blend. Set the mixture aside.

Step 3

Heat the olive oil (until it shimmers) in a 12″ cast iron skillet or oven-safe non-stick skillet. Add the mushrooms and leeks. Simmer for 2-3 minutes, stirring occasionally, until semi-tender. Add the zucchini, and cook until they're tender—about another 2-3 minutes. Add the garlic and the kippers, stirring to incorporate them with the veggies. Simmer for another minute or so.

Step 4

Give the eggs another quick whisk and carefully pour the mixture into the skillet, over the vegetables. Stir with a spatula to combine and distribute the mixture evenly across the skillet. Sprinkle the reserved cheese over the frittata, and let the frittata cook over the stove for about a minute to set the edges. (You'll see the edges slightly change color). Place the frittata in the oven, and bake for 7-10 minutes. When done, remove from the oven and let the frittata stand to cool for about 5 minutes before slicing into it.

Step 5

Garnish with freshly chopped chives, slice into appropriate portions, and serve.