Lemon Crumb Shortbread Bars

Lemon Crumb Shortbread Bars layer buttery shortbread, a bright lemon filling, and golden crumbs into one beautifully layered square. The base is tender but sturdy enough to hold its shape, while the center stays smooth and softly set. A generous crumb topping adds just enough texture without overpowering the lemon.

This recipe uses one simple shortbread mixture for both the crust and topping, so prep stays easy and cleanup stays light. Fresh lemon juice and zest keep the flavor lively, while a short chill gives the bars clean bakery-style layers. They feel polished enough for a gathering, yet simple enough for an afternoon bake with coffee or tea nearby. Serve them cold or slightly softened at room temperature, with a light dusting of powdered sugar just before serving.

Recipe Yield: 12 servings

INGREDIENTS

2 cups all-purpose flour, spooned and leveled
1 cup unsalted butter, cold and cubed
½ cup granulated sugar
¼ cup powdered sugar
½ tsp salt

Lemon Layer:
3 large eggs
3 tbsp all-purpose flour
1 cup granulated sugar
¼ tsp salt
1 tbsp fresh lemon zest
½ cup fresh lemon juice
Powdered sugar, for serving (optional)

INSTRUCTIONS

1. Preheat and prepare:
Preheat oven to 350°F. Line an 8×8-inch pan with parchment paper, leaving overhang on the sides for easy removal.

2. Make the shortbread mixture:
Whisk flour, granulated sugar, powdered sugar, and salt in a large bowl. Cut in the cold butter with a pastry cutter or clean fingertips until coarse crumbs form and the mixture holds together when pressed. Reserve 1 loosely packed cup for the topping and refrigerate it.

3. Bake the crust:
Press the remaining mixture firmly and evenly into the prepared pan. Bake for 18–20 minutes, until set and very lightly golden around the edges.

4. Prepare the lemon filling:
Meanwhile, whisk sugar, flour, salt, and lemon zest in a medium bowl. Add the eggs and whisk just until smooth. Then whisk in the lemon juice until evenly combined.

5. Begin baking the filling:
Pour the lemon filling evenly over the warm crust. Bake for 8–10 minutes, until the filling begins to set around the edges but remains loose in the center.

6. Add the crumb topping:
Working carefully, scatter the chilled shortbread crumbs evenly over the partially set filling.

7. Finish baking:
Bake for another 18–20 minutes, until the crumbs are lightly golden and the center has a gentle jiggle but no longer ripples like liquid. For extra certainty, an instant-read thermometer inserted into the center of the lemon layer should register 165–170°F (74–77°C).

8. Cool and slice:
Cool completely in the pan for about 1 hour. Then refrigerate for at least 2 hours, or until firm. Lift out using the parchment, dust with powdered sugar if desired, and slice.

Helpful Tips to Perfect This Recipe

• Keep the crumb topping cold: Refrigerating the reserved shortbread mixture helps the pieces remain distinct instead of melting into the lemon filling.
• Mix the filling gently: Whisking the flour with the sugar before adding the eggs prevents lumps. Avoid vigorous whisking, which can create excess bubbles on the surface.
• Watch the center, not just the clock: The bars are ready when the edges are set and the center moves slightly as one piece. Continue baking in 2-minute increments if it still ripples like liquid.
• Chill before cutting: The lemon layer continues to set as it cools. For clean bakery-style slices, use a sharp knife and wipe the blade between cuts.