Preheat your oven to 180°C (350°F). Remove the pie crust from the freezer and place it in a 9-inch pie dish or similar size. Prick the bottom with a fork several times to prevent excessive puffing, then partially bake according to package directions (usually 8-10 minutes) until it's just set but still pale. This prevents a soggy bottom layer later. Remove from oven and set aside to cool slightly while you prepare the filling components.

While the crust bakes, slice the leek into thin rounds (white and light green parts only) and mince the garlic cloves. Trim the woody ends from the asparagus and cut the spears into 1-inch pieces, separating the tender tips from the thicker stems. Melt the butter in a large skillet over medium heat, then add the sliced leeks and garlic, cooking for about 2 minutes until softened and fragrant. Add only the asparagus stems (not the tips yet) and cook for another 2 minutes, then remove from heat. I like to keep the asparagus tips raw at this stage—they'll cook perfectly in the custard and stay vibrant green.

Spread the sautéed leek and asparagus stem mixture from Step 2 evenly over the partially baked pie crust. Distribute 2/3 of the smoked salmon ribbons over the vegetables, followed by the gruyere cheese, which will anchor everything together and create pockets of flavor throughout the quiche.

In a bowl, whisk together the eggs, cream, fresh dill, salt, and pepper until well combined and uniform in color. Pour this custard mixture slowly over the fillings in the crust, allowing it to settle and distribute evenly. The custard should come up about 3/4 of the way up the sides of the crust. I find whisking for about 30 seconds ensures the eggs are fully incorporated, which prevents any eggy texture issues.

Place the quiche in the preheated oven and bake for about 35 minutes. Remove it briefly and arrange the reserved asparagus tips and remaining salmon ribbons on top in a decorative pattern, then return to the oven for the final 5 minutes of baking. The quiche is done when the custard is set but still slightly jiggly in the very center (about 40 minutes total), and the top has a light golden color.

Remove the quiche from the oven and let it rest at room temperature for 10 minutes before slicing. This resting period allows the custard to firm up slightly and makes for cleaner slices. Garnish with fresh dill sprigs and a few smoked salmon pieces if desired, then slice into wedges and serve warm or at room temperature.