Preheat the oven to 400 degrees. Place the rack in the lower middle of the oven.
Coat a pie pan with cooking spray then carefully unroll the pre-made pie crust and place it in the pie pan. Crimp the edges then line the unpricked crust with a double thickness of heavy-duty foil or parchment paper and pour in pie weights or dried beans in the center.
Bake for 10 minutes. Remove from the oven. Reduce oven temperature to 350 degrees.
Meanwhile, heat the butter in a small skillet over medium heat. Add the leeks and season with sea salt and freshly cracked pepper, to taste. Cook, stirring occasionally, for 10-15 minutes, until tender and starting to caramelize.
Sprinkle most of the leeks, bacon bits, and gruyere cheese in the bottom of the par-baked pie crust.
Combine the eggs and heavy cream together; whisk for 2 minutes, until very well combined. Season with sea salt and freshly cracked pepper, to taste.
Add the well-whisked egg mixture. Sprinkle with the remaining leeks, bacon bits, and gruyère cheese on top.
Carefully place into the oven and bake for 40-45 minutes, or until a knife inserted in the center comes out clean. Remove from the oven and allow to cool for 10-15 minutes before slicing and serving. Enjoy.