Apple Crumble Bar Recipe

Brown the butter

In a light-colored medium skillet, melt 12 tablespoons unsalted butter over medium heat. Swirl frequently; foam will form and then brown specks will appear and a nutty aroma will develop. Remove from heat when amber-brown (about 6–8 minutes). Pour into a heatproof bowl to stop cooking and cool 8–10 minutes.

Make dough and crumble

Whisk together 2.5 cups all-purpose flour, 1 cup rolled oats, 1 teaspoon baking powder, and 3/4 teaspoon sea salt in a large bowl. In a separate bowl, whisk the browned butter (cooled but still pourable) with 1 cup light brown sugar, 1 tablespoon granulated sugar, 1 large egg, and 1 teaspoon vanilla extract until combined. Pour the wet into the dry and stir with a spatula until coarse clumps form; the mixture should hold together when pressed. Reserve about 1 1/3 cups (roughly one-third of the total) of this mixture for the crumble topping; press the remaining mixture evenly into the bottom of a parchment-lined 9x13-inch baking pan to form the crust.

Par-bake crust

Chill the crust in the refrigerator for 10 minutes while you prepare the filling. Preheat the oven to 350°F (175°C). Bake the crust until just set and lightly golden, about 12–15 minutes. Remove from oven and set aside; reduce oven temperature to 340°F (170°C) if desired.

Top with crumble

After the apple filling is assembled on the par-baked crust and caramel added (see below), sprinkle the reserved crumble evenly over the top before the final bake.

Prepare apples: peel, core and cut 4 apples into 1/4" dice. Toss the diced apples with 1 tablespoon lemon juice to prevent browning.

Cook the filling: In a medium sauté pan over medium heat, melt 2 tablespoons butter. Add the apples, 1/2 cup light brown sugar, 2 tablespoons granulated sugar, 1 teaspoon cinnamon, and 1/4 teaspoon nutmeg. Stir and cook for 4–6 minutes until apples begin to soften and sugars dissolve. Sprinkle 1 tablespoon cornstarch over the apples, stir to combine, and cook another 1–2 minutes until the mixture thickens and glossy. Remove from heat and stir in 1/2 teaspoon vanilla extract. Allow to cool 5–10 minutes before assembling on crust.

Assemble filling on crust: Spoon the warm (not piping hot) apple filling evenly over the par-baked crust, spreading to an even layer about 1/2-inch thick.

Make the brown butter: In a small saucepan, melt 6 tablespoons unsalted butter over medium heat, swirling frequently until it turns golden brown and smells nutty, about 4–6 minutes. Watch carefully to avoid burning. Remove from heat.

Make the caramel: Return the brown butter to low heat, add 3/4 cup light brown sugar and stir until dissolved. Carefully whisk in 1/2 cup heavy cream a little at a time (mixture may bubble vigorously). Simmer gently for 2–3 minutes until slightly thickened. Remove from heat and whisk in 1/2 teaspoon sea salt and 1/2 teaspoon vanilla extract. Let caramel cool 5 minutes.

Layer caramel: Drizzle about 3/4 cup of the warm (not hot) brown-butter caramel evenly over the apple layer in the pan, leaving a little to serve with slices. Save any remaining caramel in a jar for serving; if it firms up too much, gently rewarm to drizzle.

Final bake: Sprinkle the reserved crumble evenly over the caramel-topped apples. Bake in the preheated 350°F (175°C) oven for 25–30 minutes, until the top is golden brown and juices are bubbling at the edges. If the top browns too quickly, tent loosely with foil for the last 10 minutes.

Cool and slice: Remove from oven and cool on a wire rack at least 30 minutes to let filling set. Run a knife around the edges and, once mostly cooled, lift the bars out using the parchment. Transfer to a cutting surface and cut into 12 equal bars. Rewarm reserved caramel slightly if needed and drizzle over bars just before serving.

Prepare ice cream base: Chill a mixing bowl and whisk or the bowl of a stand mixer in the freezer for 10 minutes. Pour 2 cups cold heavy cream into the chilled bowl and whip to soft peaks. In a separate bowl, stir together 1 can sweetened condensed milk, seeds from 1 vanilla bean (or 1 tsp paste), 2 tablespoons bourbon, and 1/8 teaspoon salt until smooth.

Combine and freeze: Fold one-third of the whipped cream into the condensed milk mixture to lighten, then gently fold in the remaining whipped cream until homogeneous. Pour into a loaf pan or airtight container, smooth the top, cover with plastic wrap (press to surface) and freeze at least 6 hours or overnight until firm.

Serve: When ready to serve, remove ice cream from freezer 5–10 minutes to soften slightly. Scoop alongside warm apple crumble bars. Optionally drizzle extra brown-butter caramel and sprinkle a few flaky sea salt flakes and a small splash of bourbon (to taste) over each serving.