Step 1: Preheat your oven to 400°F (200°C). Toss the pumpkin cubes with olive oil, salt, and pepper, then roast on a baking sheet for 15-20 minutes until tender and slightly browned.
Step 2: While the pumpkin roasts, lower the oven temperature to 375°F (190°C). Fit the pie crust into a 9-inch pie dish, prick the bottom with a fork, and blind bake for 10 minutes using pie weights or dried beans.
Step 3: Sauté the minced garlic and spinach in a pan over medium heat until the spinach is completely wilted. Remove from heat and squeeze out any excess liquid using a clean kitchen towel.
Step 4: In a large mixing bowl, whisk together the eggs, heavy cream, milk, nutmeg, salt, and pepper until the mixture is smooth and well-combined.
Step 5: Layer the roasted pumpkin, sautéed spinach, and crumbled feta cheese into the bottom of the pre-baked pie crust.
Step 6: Pour the egg mixture over the fillings and sprinkle the top with Parmesan cheese.
Step 7: Bake the pumpkin and spinach quiche for 35-40 minutes, or until the filling is set and the top is golden brown. Let it rest for 15 minutes before serving.