Preheat your oven to 375°F (190°C) and prepare your pre-made pie crust in a 9-inch pie dish.

In a large skillet, heat olive oil over medium heat and sauté diced onion, mushrooms, and butternut squash for 5-7 minutes.

Stir in chopped kale and cook for an additional 2-3 minutes until wilted. Remove from heat.

In a mixing bowl, whisk together eggs, milk, salt, and pepper until frothy.

Assemble the quiche by spreading the vegetable mixture in the pie crust and pouring the egg mixture over it.

Bake in the preheated oven for 35-40 minutes until golden-brown and the filling is set.

Allow to cool for 5-10 minutes before slicing and serving warm.