Gather all ingredients and necessary equipment, and preheat your oven to 375°F (190°C). If using a store-bought pie crust, let it sit at room temperature.

In a large mixing bowl, crack the eggs and add the milk. Whisk until the mixture is smooth and well combined. Season with salt and pepper.

Chop asparagus, spinach, and bell peppers into bite-sized pieces. Sauté in a non-stick skillet over medium heat for about 3-5 minutes.

Stir the sautéed vegetables into the egg and milk mixture, followed by the shredded cheese. Ensure even distribution.

Pour the mixture into the prepared pie crust and bake for 35-40 minutes until golden brown and set.

Let the quiche cool for about 10 minutes, slice, and serve.