Preheat oven to 400°F. Arrange pie crust in pie pan and crimp edges as desired. Chill crust in the freezer for 30 minutes.
Line the inside of the crust with foil or parchment, then fill with pie weights or dry beans. Bake crust for 20 minutes, then remove foil and weights and bake another 8 minutes. Let cool and reduce oven to 350°F.
Place a saute pan over medium heat and add olive oil, swirling the pan to coat. Add the spinach and cook a few minutes until bright green and wilted. Remove from heat and set aside.
In a bowl, whisk together eggs, cream, milk, salt, garlic powder, mustard powder, nutmeg, and pepper until smooth and blended.
Scatter half the cheese into the bottom of the baked crust, then add the spinach. Pour over the egg mixture, then top with remaining cheese.
Carefully transfer pie plate to the oven (you can place on a baking sheet if desired) and bake at 350°F for 40-45 minutes, until lightly browned and center is just barely jiggly.