Preheat oven to 400ºF.
Heat a heavy-bottomed pan over medium heat and render the bacon until crispy.
Remove the bacon from the pan to drain on paper towels, saving the fat for another use.
In the same pan, sauté the onions, apples, and sage until tender. Remove from the heat and allow to cool slightly.
While the bacon mixture is cooling, press the pie crust into a pie dish and bake for about 10 minutes, or until just golden brown.
Drop the oven temperature to 325ºF.
Whisk together the eggs, half and half, and cheese.
Spread the bacon mixture evenly over the bottom of the par-baked pie shell.
Pour the egg mixture over the top and bake for about 30-40 minutes, or until set and golden brown.
Remove from the oven and allow to cool for 5-10 minutes. Slice and serve warm.