Step 1: Preheat the oven

• Preheat your oven to 375°F (190°C). Grease a 9-inch pie dish or baking dish with butter or nonstick spray.

Step 2: Sauté the vegetables

• In a skillet over medium heat, heat olive oil or butter. Add the onion and cook until softened about 3–4 minutes.
• Add the diced vegetables and cook until tender, about 5 minutes. If using spinach, cook until wilted. Remove from heat and let cool slightly.

Step 3: Prepare the egg mixture

• In a large mixing bowl, whisk together the eggs, heavy cream, milk, salt, and pepper until well combined.

Step 4: Combine ingredients

• Stir the sautéed vegetables, cheese, and cooked bacon or ham (if using) into the egg mixture. Add fresh herbs for extra flavor.

Step 5: Assemble and bake

• Pour the mixture into the prepared pie dish.
• Bake for 30–35 minutes, or until the quiche is set and the top is lightly golden. Insert a knife in the center; it should come out clean.

Step 6: Cool and serve

• Let the quiche cool for 5–10 minutes before slicing. Serve warm or at room temperature with your favorite side dishes.