Prepare the vegetables: Wash and clean all the vegetables. Slice the mushrooms, zucchini, garlic cloves, leeks and onion. Set the temperature of the stove to medium-low and add the cooking oil to the pan. Brown the onion and garlic for six to eight minutes until it is golden and caramelized.
Sauté the vegetables: Add the mushrooms and cook for five minutes. Add the spices. Add the zucchini and leeks. Add the corn and mix. Turn off the heat.
Make the Savoury custard base: Crack two eggs, add it to a bowl, add the fresh cream and milk to the bowl. Add garlic powder, white pepper powder and salt and whisk well.
Bake: Transfer the vegetables to a casserole, make sure to even it out, then pour the custard mixture and sprinkle on grated cheddar cheese. Bake for 30 minutes at a temperature of 175 ℃. Thereafter, remove from the oven and let it rest for five minutes so that it settles down and serve.