Preheat the oven to 350°F (175°C).
Slice the potatoes and toss them with 2 tablespoons of olive oil and a little bit of salt and pepper.
Spread the potatoes on a baking sheet lined with parchment paper. Bake for about 15 minutes, or until the potatoes are soft and beginning to turn a golden brown.
Remove the potatoes from the oven and allow them to cool.
Drop the oven temperature to 325°F (165°C).
In a skillet over medium heat, fry the 3 slices of bacon.
When the bacon is done, remove the slices from the skillet and allow them to cool. Once cool, chop them into bacon bits.
Using the same skillet, caramelize the onions in the bacon grease on low heat. Truly caramelizing onions takes a long time, about 45 minutes. Keep the heat on low and stir the onions every 10 minutes until they’re a golden brown color. Remove the onions from the heat and allow them to cool.
Mix together the potato slices, bacon bits, and caramelized onions. Once cooled, spread them over the bottom of your prepared, fully-baked pie crust.
In a large mixing bowl, whisk together the eggs, milk, cream, salt, pepper, chives, and shredded cheese until smooth and fully combined.
(Optional) Lightly brush the edges of your dark, blind-baked pie crust with heavy cream for a beautiful golden finish after baking.
On a metal sheet pan, pour the quiche mixture into the prepared crust, filling it just below the rim to prevent overflow.
Transfer the quiche to the oven and bake for 35–40 minutes, or until the edges are puffed and the center is still slightly jiggly. The filling will continue to set as it cools.
Remove the quiche from the oven and let it cool on the countertop for at least 30 minutes before slicing and serving.