Prepare the Crust

• Make the Dough: In a food processor, pulse the flour, butter, and a pinch of salt until the mixture resembles coarse crumbs. Gradually add ice water, one tablespoon at a time, and pulse until the dough just comes together.
• Chill the Dough: Form the dough into a disk, wrap in plastic wrap, and refrigerate for at least 30 minutes.
• Roll Out the Dough: On a lightly floured surface, roll out the chilled dough to fit a 9-inch tart pan. Press it into the pan and trim the edges. Prick the bottom with a fork and refrigerate for another 15 minutes.
• Pre-Bake the Crust: Preheat the oven to 375°F (190°C). Line the crust with parchment paper and fill with pie weights or dried beans. Bake for 15 minutes, then remove the weights and parchment and bake for another 5 minutes. Set aside to cool slightly.

Prepare the Filling

• Blanch the Asparagus: Bring a pot of salted water to a boil. Add the asparagus and blanch for 2-3 minutes, or until just tender. Transfer to an ice bath to stop cooking, then pat dry. Trim to fit the tart pan if needed.
• Make the Custard: In a mixing bowl, whisk together the eggs, heavy cream, salt, pepper, and nutmeg (if using).

Assemble and Bake

• Layer the Filling: Arrange the asparagus in the pre-baked crust. Sprinkle the grated Gruyère and Parmesan cheese over the asparagus. Pour the custard mixture over the top, ensuring it spreads evenly.
• Bake the Quiche: Bake at 375°F (190°C) for 30-35 minutes, or until the filling is set and the top is golden brown.
• Cool and Serve: Allow the quiche to cool for 10 minutes before slicing. Serve warm or at room temperature.