Preheat your oven to 375°F (190°C).

Prepare the crust: Place the pie crust into a 9-inch pie dish. If using a store-bought crust, you can slightly pre-bake it for 5-7 minutes to prevent sogginess.

Sauté the vegetables: In a medium pan, heat olive oil over medium heat. Add the onion, asparagus, and peas, and sauté for 3-4 minutes until the vegetables are tender. Add the spinach and cook for another 2 minutes until wilted. Set aside to cool slightly.

Prepare the filling: In a large bowl, whisk together the eggs, heavy cream, milk, garlic powder, salt, and pepper.

Assemble the quiche: Evenly spread the sautéed vegetables on the bottom of the pie crust. Pour the egg mixture over the vegetables. Sprinkle the cheddar and feta cheeses on top.

Bake: Place the quiche in the oven and bake for 35-40 minutes, or until the center is set and the top is golden brown.

Cool: Let the quiche cool for 5-10 minutes before slicing and serving.