Brown Sugar Pie Bars have a soft brown sugar filling atop a buttery shortbread base, like pecan pie bars without the pecans. Based on a Southern Brown Sugar pie, these richly flavored bars are a portion-controlled piece of slab pie and a real crowd pleaser!
Make the shortbread base: Preheat the oven to 350 °F. Line an 13- x 18-inch half sheet baking pan with two pieces of parchment paper or aluminum foil, leaving an overhang all around to help lift the bars out of the pan later. (See the Recipe Notes on how to scale down the recipe to use a smaller pan size.)
Using a mixer: In the bowl of a stand mixer fitted with a paddle attachment, cream the butter and sugar together until smooth. Add the flour and salt and mix just until a dough forms.
Mixing by hand: Whisk the flour, powdered sugar, and salt together in a medium bowl. Using a pastry blender, cut in the butter until the mixture resembles coarse crumbs.
Continuing: Press the shortbread into the prepared baking pan. Using plastic wrap and a pie pan roller helps get everything even without making too much of a mess.
Par-bake the shortbread for 15 minutes or until light brown. Watch that the shortbread crust doesn’t get too dark - at 20 minutes, the crust is medium-dark brown.
Make the filling: While the crust is baking, whisk the eggs in a large bowl. Add the brown sugar, butter, vanilla, and salt. Whisk together until the filling is well combined and smooth.
Remove the pan from the oven and pour the filling on top of the hot shortbread. Return the pan to the oven and bake until the filling is set, about 25 to 30 minutes. It will puff up but will settle down when cooling. Don't bake for more than 35 minutes or the filling can get too firm.
Cool the bars completely in the pan on a wire rack. Chill the bars for 15 minutes before removing the slab from the pan.
Lift the uncut slab out of the pan using the parchment paper or foil overhang and transfer to a cutting board, being careful not to bend the slab. Cut the slab into 2- x 2-inch squares. See the Recipe Notes regarding cutting hints.
Serve and enjoy the pie goodness in a bar!
Storage instructions: Store the bars in an airtight container at room temperature for up to 3 days, or in the refrigerator for a week. You can also freeze the bars in an airtight bag for longer storage.
Recipe Notes
Dark brown sugar has almost twice the amount of molasses in it than does light brown sugar. Here using dark brown sugar will really emphasize the molasses flavor, or ease off by using light brown sugar.When cutting the bars, it might be necessary to trim the edges for a cleaner slice. It's easiest to cut the bars using a pizza cutter. If you use a knife, just wipe the blade after each time you slice.Pan size alternatives: This recipe can be scaled down using the recipe amounts below - the bar thickness and total yield will depend on the pan size used (with some leftover trimmings):
For the Crust
½ cup unsalted butter (113 grams)
½ cup powdered sugar (56 grams) or ¼ cup granulated sugar (50 grams)