Preheat the oven according to the pie crust instructions.

Roll out the pie crust and place it in a quiche or pie dish.

In a pan, sauté the sliced mushrooms until softened.

Add the chopped spinach to the pan and cook until wilted.

In a bowl, whisk together the eggs, milk, salt, black pepper, and nutmeg.

Stir in the sautéed spinach and mushrooms along with the shredded cheese.

Pour the mixture into the prepared pie crust.

Bake in the preheated oven for the time specified on the pie crust packaging, or until the filling is set and the top is golden brown.