1-Step 1: Heat the oven and prep the pan Start by heating your oven to 350°F. Line an 8×8-inch baking pan with parchment paper, leaving some overhang if you can, because that makes it much easier to lift the bars out later. This is a good time to peel, core, and thinly slice your apples into 1/8-inch pieces so the filling comes together fast.

2-Step 2: Brown the butter Place 1 1/2 sticks of unsalted butter in a skillet and melt it over medium heat. Keep cooking until the butter turns golden brown and smells nutty. Stir in 3/4 teaspoon kosher salt, then set it aside for a few minutes. If you are short on time, regular melted butter will still work, but the brown butter gives Brown Butter Apple Shortbread Bars their best flavor.

3-Step 3: Mix the shortbread dough In a large bowl, whisk together 2 cups all-purpose flour, 1/3 cup granulated sugar, 1/3 cup packed light brown sugar, and 3/4 teaspoon baking powder. Pour in the browned butter and stir until the mixture forms a dough. It should look a little crumbly at first, then come together as you mix. Reserve 3/4 cup of this dough for the topping, then press the rest evenly into the bottom of the prepared pan.

4-Step 4: Bake the crust Bake the crust for about 15 minutes at 350°F. You want it set and just starting to color, not fully browned. This quick first bake helps keep the bottom from getting soggy once the apple filling goes on top.

5-Step 5: Make the apple filling Increase the oven temperature to 375°F. In another bowl, whisk together 2 large eggs, 1/3 cup granulated sugar, 1/3 cup packed light brown sugar, 2 tablespoons all-purpose flour, 2 tablespoons heavy cream, 1 teaspoon apple pie spice, and 1/4 teaspoon kosher salt. Toss the sliced apples into the mixture until every piece is coated. The flour and eggs help the filling set, while the spice and sugars create that classic apple-bar flavor.

6-Step 6: Assemble the bars Spread the apple mixture evenly over the partially baked crust. Then crumble the reserved dough over the top. You do not need to cover every inch perfectly. A rustic layer of crumbs gives the bars a nice homemade look and lets the apples peek through while baking.

7-Step 7: Bake until golden and thickened Bake for 55 to 60 minutes, or until the top is golden and the filling looks thickened and set. If you are using a 9×9-inch pan, start checking around 45 minutes since the bars will be thinner. The finished bars should look puffed, lightly browned, and fragrant.

8-Step 8: Cool, slice, and serve Let the bars cool completely before slicing. This is important because the filling continues to set as it cools. Once firm, lift the bars out of the pan and cut them into 12 to 16 pieces. Serve them as-is, or add a small scoop of vanilla ice cream if you want a simple dessert plate.