Step 1

Preheat the oven to 450 degrees F (230 degrees C). Press pie crust into the bottom and up the sides of an 11-inch tart pan.

Step 2

Bake in the preheated oven until golden, 10 to 12 minutes. Remove and let cool.

Step 3

Reduce the oven temperature to 325 degrees F (165 degrees C).

Step 4

Place bacon in a large skillet and cook over medium-high heat, turning occasionally, until evenly browned, about 10 minutes. Drain bacon slices on paper towels. Crumble.

Step 5

Heat bacon grease in the same skillet over medium-high heat. Add onion and saute until translucent, about 5 minutes. Add apple and cook until just tender, 3 to 5 minutes. Add garlic and saute until fragrant, about 1 minute. Remove from heat and stir in bacon.

Step 6

Whisk milk, sour cream, eggs, sea salt, and cinnamon together in a bowl.

Step 7

Layer apple mixture, Cheddar cheese, and egg mixture in the prepared crust. Sprinkle sage over top.

Step 8

Bake in the preheated oven until set, 30 to 40 minutes. Allow to cool before serving.