Heat a large heavy bottom skillet over medium-high heat. Add the cinnamon stick, whole cloves, black peppercorns and toast until fragrant, about 1 to 2 minutes. Shake the pan occasionally to ensure the spices toast evenly on all sides. Add the ground nutmeg for the last 10 to 15 seconds and transfer the mixture to a pestle and mortar or spice grinder. Grind until a find powder forms and reserve.
Return the skillet to the heat, add the butter and melt. Add the peeled, sliced, and cored apples with a small pinch of kosher salt and cook for 3 minutes until the natural juices begin to release from the apples.
Add the brown sugar and cook for an additional 3-minutes.
Remove from heat and and stir in the lemon juice, lemon zest, prepared spice mixture, vanilla bean (or extract), kosher salt, and stir to combine.
Transfer filling mixture to a 9 x 13-inch baking dish and allow to cool slightly while preparing the topping.
Crumble Topping - (Either Flour Method)
Add all of the dry ingredients to a medium sized mixing bowl and whisk to combine.
Add in the cold, cubed, unsalted butter and work into the dry ingredients with your hands or a pastry cutter until a sandy consistency forms. The mixture will be clumpy; continue to work the mixture together until any clumps are no larger than pea-sized.
Baking
Spread the crumble topping mixture evenly over the apple filling and bake for 40 - 45 minutes until golden brown and bubbling.
Remove from the oven and allow to cool slightly. Serve warm.
Notes
Serve warm, with a scoop (or two!) of your favorite vanilla ice cream!