Cut the zucchini and leek into medium-size rings. Break asparagus in half and then 2-3 more times. Finely chop the parsley, garlic, and onion.
You can use other seasonal vegetables too, such as mangel, spring onion, peppers, and more. Frittata can also be made with prosciutto and bacon. There are a lot of recipes out there and people use all sorts of ingredients, so you can always include some of your favorites.
Stir the eggs, add milk, salt, pepper, and flour. Mix together all the ingredients.
Heat the butter in the pan until it melts and then add all the vegetables except the parsley, garlic, and onion.
Let all the ingredients bake on the light fire for about 5 minutes.
Add the rest of the vegetables (parsley, onion, and garlic).
Bake together all the ingredients for just a few minutes.
Add the mixture with eggs and lower the fire to the minimum. Let it all rest for 5 to 10 minutes.
Remove it from the fire and add parmesan.
Turn on the oven (only the top heater) and set it to 200 °C (392 F). Once the oven reaches the desired temperature, put the mixture in.
When the cheese melts and you see that the top layer gets a light golden color, the dish is done.
Turn off the oven and take out the dish.
Let it cool for a few minutes and then cut it into 4 pieces.