Prep. Preheat the oven to 350 F. Prep your pie crust and press it into a 9" quiche or pie pan. If prebaking (not necessary with my recipe), allow it to cool completely before adding the filling. Place quiche/pie pan on a rimmed baking sheet before filling.
Bacon. Cook bacon (7 slices) in a medium skillet until crispy, about 8 to 10 minutes. Place cooked bacon on a paper towel-lined plate. Once cool enough to handle, chop into small pieces.
Saute. Add onions (1/2 chopped) and chopped leeks (1/2 cup), and saute in the bacon fat (note 4) until softened, about 5-7 minutes. Sprinkle bacon, onions, and leeks along the bottom of your pie crust, followed by half the cheese.
Combine. In a medium bowl, whisk eggs (6). Add heavy cream (1 cup), salt (1/2 teaspoon), a dash of white pepper, nutmeg (1/8 teaspoon), fresh thyme (1 teaspoon), and combine. Pour into the pie crust, and sprinkle the remaining cheese on top.
Bake for 30-35 minutes, you'll know the quiche is done once it has set completely in the center. Allow quiche to cool slightly before serving.