Caramel Apple Crumble Bars

1. Make the caramel (see recipe below). Set aside to cool.
2. Preheat the oven to 350℉. Line a 9×9-inch baking pan with parchment paper, leaving about an inch overhang on two sides. Set aside.
3. Make the crumble: In a large mixing bowl, whisk together the oats, flour, sugars, baking soda, and spices until well-combined.
4. Cut the butter into cubes, then use a pastry blender to cut the butter into the dry ingredients. Once it’s mostly combined, switch to using your fingers and knead until completely incorporated. You should form a shaggy, crumbly dough, that easily sticks together when pinched. This may take a few minutes.
5. Prep the filling: Using a mandolin, or a very sharp knife, (carefully) cut the apples into slices, as thin as you can manage.
6. Assemble: Scoop about two thirds of the crumble dough into the baking pan, and press into an even layer along the bottom. Layer the apples across the bottom crust.
7. Drizzle the (room-temperature) caramel sauce across the apples, adjusting the amount to taste. Top with the remaining crumble mixture, from edge to edge. Sprinkle with the chopped walnuts, if using. Press the crumb topping down gently.
8. Bake for 35-45 minutes, until the crumble topping is golden brown and has puffed up a bit. The caramel may be starting to bubble up through the crumbs. Remove from the oven and let cool completely on a baking rack before cutting into bars. Enjoy!!

Simple Caramel Sauce

1. Melt the sugar in a medium heavy-bottomed pot (preferably with high sides) over medium heat, stirring constantly. The sugar will begin to form clumps, then melt into a deep amber-colored liquid as you stir. Be careful not to let the sugar burn.
2. Add the cubed butter as soon as the sugar is completely melted, and whisk until smooth. Remove from the heat and slowly stir in the cream. The mixture will foam and bubble up. Keep whisking until the caramel is smooth. Stir in the vanilla. Season with salt, to taste.
3. Let cool for a few minutes in the pan, then transfer to a heat-proof jar and let cool to room-temperature. Will keep for up to two weeks, stored in an air-tight jar in the refrigerator. Warm before serving.