Preheat the oven to 350 degrees F.
Whisk together eggs, yogurt, salt and pepper and set aside.
12 large eggs, 1 cup 2% plain Greek yogurt, 1 ½ teaspoon salt, ½ teaspoon freshly ground black pepper
Trim the dark green parts of the leeks and cut off the root end. Cut leeks in half lengthwise and then slice thinly. Place in a large bowl and rinse under cold water to remove all the sand. Let sit for 2 minutes so the sand can settle to the bottom of the bowl then lift the leeks out and into a colander to drain.
2 leeks,
Mix the 2 cheddars together but keep the feta in a separate bowl.
100 g feta cheese crumbled or cubed,, 100 g aged white cheddar,, 50 g smoked cheddar,
Heat oil or butter in a 12-inch cast iron skillet or oven-proof skillet over medium-high heat. Add leeks and cook, stirring often until starting to soften, 2 to 3 minutes.
2 teaspoon olive oil or butter
Add zucchini and continue cooking, stirring often until zucchini are softened, 5 to 6 minutes.
2 zucchini,
Stir in peas, spinach, and dill making sure everything is distributed evenly in the pan before adding the egg mixture.
1 cup green peas,, 4 cups chopped spinach or baby spinach,, ¼ cup fresh dill, chopped
Remove from heat and pour in the egg mixture distributing it evenly around the pan. Add the feta and top with cheddar cheese mixture.
Bake for 25 to 30 minutes or until just set. Optional: turn broiler on to brown the top. This will only take 1 or 2 minutes so keep an eye on it.