How to Make It
Prepare the Crust: Whisk together flour, cookie crumbs, sugar, and salt in a large bowl. Add cold butter pieces to bowl, and use fingertips to work butter quickly into flour mixture. Using a fork, stir buttermilk, 1 tablespoon at a time, into flour mixture until moistened and dough begins to come together.
Gently knead dough until it comes together completely (2 to 3 times). Press into a disk and wrap tightly with plastic wrap; chill 1 hour.
Preheat oven to 375°F. Remove dough from refrigerator. Roll dough into an 11-inch round on a lightly floured surface. Transfer dough to a 9 1/2-inch deep-dish pie plate; gently press into edges of dish and seal any tears. Fold overhanging dough over edge of dish to form a crust (crimp as desired). Chill until ready to fill.
Prepare the Cookie Butter Caramel: Heat butter and brown sugar in a medium saucepan over medium-low, stirring often, until butter and sugar melt. Whisk in cookie butter until melted and combined. Whisk in half-and-half, and cook, whisking constantly, until smooth and heated through. Remove from heat, and stir in salt.
Prepare the Filling: Bring 8 cups water to a boil in a large saucepan over high. While water is heating, peel, core, and slice apples and pears into 1/8-inch-thick slices; transfer fruit to a large heatproof bowl. When water reaches a boil, pour over fruit; let stand 10 minutes. Drain well; pat slices dry with a clean towel. Return fruit to bowl.
Sprinkle sugar, flour, vinegar, vanilla, cinnamon, and salt over fruit; toss gently to combine. Stir in 1 1/2 cups of the prepared Cookie Butter Caramel.
To assemble pie, pour Filling into prepared Crust; gently press into an even layer using a rubber spatula. Place pie on a rimmed baking sheet (to catch any spills). Bake in preheated oven for 25 minutes.
Prepare the Topping: Whisk together flour, cookie crumbles, pecans, brown sugar, and salt in a medium bowl. Cut butter into flour mixture using a fork or your fingertips until clumps form. Sprinkle Topping evenly over pie. Increase oven temperature to 400°F,and bake until topping is golden brown, 15 to 18 minutes. Cool slightly before cutting.