A combination of half and half and whole eggs creates a tender custard for bacon, cheese and sautéed onions. Use a meltable, shredded, white cheese like swiss or gruyere for the best custard feel.
Preheat oven to 350°F. Pre-bake frozen pie shell for 40 minutes as directed in my all-butter pie crust recipe.
While pie shell is baking, whisk the half and half, eggs and white pepper in a bowl or 4-cup measuring cup and set aside. Fry the bacon in a large skillet over medium heat until browned. Transfer to a paper-towel lined plate to drain, then slice or break into 1/2-inch chunks. Reserve 1 tablespoon of the clear, rendered bacon fat, discard the rest, and carefully wipe out the warm skillet. Add the bacon fat back to the skillet and cook the onion over medium heat for 4-5 minutes or until tender, and set aside.
Once pie shell has pre-baked, remove from the oven and raise the temperature to 375°F. Scatter the cheese on the pre-baked pie shell then top with the bacon and onion. Slowly pour in the custard mixture over the bacon mixture. Bake for 30-35 minutes or until the top of the quiche puffs and begins to brown and a cake tester or toothpick comes out clean while the center may still be somewhat jiggly.
Transfer to a cooking rack where the egg will continue to set. Cut into slices and serve warm or at room temperature. If making ahead, bring to room temperature for 15-30 minutes before serving.