1-Step 1: Heat the oven and brown the butter Start by heating your oven to 350°F. Place 1 1/2 sticks unsalted butter in a skillet over medium heat and melt it slowly. Keep cooking until the butter turns golden brown and smells nutty, then stir in 3/4 teaspoon kosher salt. Let it cool slightly so it does not scramble the dry ingredients when you mix the dough. If browning butter is not possible, regular melted butter will still work. You will miss a little of that deep toasted flavor, but the bars will still taste delicious and buttery.

2-Step 2: Prep the pan and mix the dry ingredients Line an 8×8-inch baking pan with parchment paper so you can lift the bars out later. 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. This dry mix gives the shortbread its structure and sweet, tender crumb. Keep the parchment paper long enough to hang over the sides if possible. Those little overhangs make removal much easier once the bars have cooled.

3-Step 3: Form the shortbread dough Pour the browned butter into the flour mixture and stir until a dough forms. It should look crumbly at first, then come together as you mix. Reserve 3/4 cup of the dough for the topping, then press the rest evenly into the prepared pan. The bottom layer should feel packed and even, but do not press so hard that it becomes dense. A gentle, firm press gives you a base that bakes up tender instead of tough.

4-Step 4: Bake the crust Bake the crust for about 15 minutes, just until it is lightly golden around the edges. This first bake helps set the base so it can support the apple filling without turning soggy. While it bakes, you can move on to the filling ingredients. If you are making a thinner version in a 9×9-inch pan, start checking earlier, around the 45-minute mark once the topping goes on. The bars will bake a little faster in a larger pan.

5-Step 5: Make the apple filling Increase the oven temperature to 375°F. In a 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. The mixture should look smooth and slightly thick. Now add 1 1/4 pounds of peeled, cored, and thinly sliced apples. Toss well so every slice gets coated. This step helps the apples bake evenly and keeps the spice mixture distributed throughout the bars.

6-Step 6: Assemble and bake again Spread the apple mixture evenly over the hot crust. Crumble the reserved dough over the top so some apples peek through. That scattered topping gives the bars a rustic look and a nice mix of crisp and tender textures. Bake for 55 to 60 minutes, or until the top is golden and the apple filling looks thickened and set. If your apples are especially juicy, you may need the full bake time. For a softer spice profile, you can use pumpkin pie spice instead of apple pie spice.

7-Step 7: Cool, slice, and serve Let the bars cool completely before cutting. This is the part that takes patience, but it matters because the filling finishes setting as it cools. Once cooled, lift the parchment out of the pan and cut into 12 to 16 pieces. For the cleanest slices, wait until the bars are fully cool. Warm bars taste great, but they can be a little messy when you cut them too soon. Serve them plain, or add a dusting of powdered sugar if you want a bakery-style finish. These Brown Butter Apple Shortbread Bars are lovely with coffee, tea, or a simple glass of milk.