Prepare Ingredients: Wash and slice mushrooms and zucchinis. Slice the onion, cube the bell peppers, and drain the sweet corn. Thaw and blind bake the short crust pastry.
Sauté Vegetables: Preheat a wok to medium-low heat. Add cooking oil and sauté onions for four minutes. Remove onions, then add zucchinis, bell peppers, sweet corn, salt, black pepper, and nutmeg to the wok.
Combine Mixture: Transfer sautéed vegetables to a casserole. Whisk eggs with milk, salt, and pepper, then pour over the vegetables. Cream is optional.
Add Cheese and Bake: Top with grated mozzarella cheese. Bake in a preheated oven at 175ºC / 350ºF for 20 minutes with the fan on, then 5 minutes without the fan. Total bake time is 40-45 minutes. Serve the quiche.