Brown the Butter: Preheat your oven to 375°F (190°C). Place 6 tablespoons of butter in a 10-inch black cast-iron skillet over medium heat on the stovetop. Swirl the pan continuously as the butter melts, foams, and crackles. After 3 to 4 minutes, nutty golden-amber specks of toasted milk solids will form on the bottom. Immediately pour the brown butter into a medium mixing bowl, leaving a thin glaze in the skillet to coat the pan.

Make the Brown Butter Oat Pecan Crumble: To the bowl of warm brown butter, add the rolled oats, 1/2 cup flour, 1/2 cup packed dark brown sugar, chopped pecans, 1/2 teaspoon cinnamon, vanilla bean extract, and flaky sea salt. Stir with a fork until large, buttery clumpy clusters form. Place the bowl in the freezer for 5 minutes to firm up slightly while preparing the apples.

Toss & Sauté the Spiced Apples: In the same cast-iron skillet set over medium heat, add the sliced Honeycrisp and Granny Smith apples. Stir in 2 tablespoons maple syrup, 2 tablespoons brown sugar, fresh lemon juice, 1 tablespoon flour, 1 teaspoon cinnamon, and nutmeg. Cook, stirring gently, for 4 to 5 minutes until the apples release their juices and begin to soften into a bubbling cinnamon caramel syrup.

Assemble & Bake to Golden Perfection: Remove the skillet from heat and level the spiced apples into an even layer. Retrieve the chilled brown butter crumble from the freezer and scatter it generously over the bubbling apples, leaving a few pockets around the edges visible for caramel bubbles to peek through. Transfer the skillet directly to the preheated oven and bake at 375°F (190°C) for 22 to 25 minutes, until the oat crumble is deeply golden-brown and fragrant, and the fruit juices bubble vigorously around the perimeter.

Rest & Crown with Ice Cream: Let the apple crisp rest on a cooling rack for 5 to 7 minutes to allow the caramel juices to thicken slightly. Spoon generous warm portions into rustic ceramic dessert bowls, crown immediately with a cold scoop of vanilla bean ice cream, and let it melt into the warm spiced caramel. Serve immediately.