Arrange the pie crust in your pie plate. Fold the overhanging edges under on itself and either use the tines of a fork to press the edges onto the rim of the pie plate, or create an edge by pinching the thumb and forefinger together and pressing the dough into the crease using the forefinger of your other hand - follow the rim of the crust until completely crimped. Bake for 8-9 minutes until lightly browned. Set aside.
Reduce oven temperature to 350 degrees.
Add the potatoes to a small pan of water and bring to a boil. Reduce heat to simmer and cook until potatoes are tender, about 7-10 minutes. Drain potatoes and set aside to cool.
Meanwhile crack the eggs into a large bowl. Add the salt and pepper and whisk until combined. Add the milk and cream and whisk again. Add the bacon, potatoes, scallions, rosemary, chives, and cheeses and stir together until well combined.
Pour the egg mixture into the prepared pie shell. Smooth the ingredients evenly into the crust and sprinkle with remaining cheeses. Bake for 45 minutes to 1 hour until custard is set. Let rest for 20-30 minutes before cutting.
Can be made a day ahead and rewarmed the next day at 300 degrees for 20 minutes.