Preheat your oven to 190°C (375°F). Roll out the pie crust on a floured surface to about 3mm thickness, then fit it into your tart pan. Chill the crust for 15 minutes to relax the dough.
Line the chilled crust with parchment paper and fill with pie weights or dried beans. Bake until golden around the edges, about 20 minutes. Remove the weights and parchment, then bake for another 5 minutes to crisp the bottom.
While the crust bakes, prepare the asparagus by snapping off the woody ends and slicing on a bias. Sauté the asparagus in olive oil over medium heat for 3-4 minutes until tender and fragrant. Set aside to cool slightly.
Wash the spinach thoroughly and chop roughly. In the same skillet, wilt the spinach with a pinch of salt for 1-2 minutes until just tender. Drain any excess moisture and set aside.
In a mixing bowl, whisk together the eggs, heavy cream, nutmeg, salt, and pepper until just combined and slightly frothy.
Spread the wilted spinach evenly over the partially baked crust, then layer the sautéed asparagus on top. Pour the custard mixture over the greens, ensuring it spreads evenly.
Sprinkle the grated Gruyère cheese over the top, distributing it evenly for meltiness and flavor.
Bake the quiche in the oven for 35-40 minutes, until the top is bubbly and golden, and the filling is set but still slightly wobbly in the center.
Remove the quiche from the oven and let it rest for about 10 minutes. This resting period helps the filling firm up and makes slicing easier.
Slice the quiche into wedges and serve warm or at room temperature. Enjoy the tender greens, creamy custard, and crispy crust in every bite.
