These lemon bars have a buttery shortbread base topped with a bright, sweet-tart lemon layer. The fresh lemon flavor is like sunshine — perfect for spring and summer. They use just seven simple ingredients and set up cleanly for easy slicing. 
Lemon bars are a timeless treat every baker should know. The combination of a rich shortbread base and a silky lemon topping delivers bright citrus flavor without being overly sour or cloyingly sweet. Because lemons are available year-round, this recipe is great anytime you want a zesty, refreshing dessert.
The Best Lemon Bar Recipe
After testing multiple versions, I balanced sweetness, lemon intensity, and texture so the lemon layer sets reliably. Highlights of this recipe:
- Thick, buttery shortbread base to balance the lemon topping
- Lemon layer that’s tangy and sweet without tasting sour
- Consistent set for clean slices
- Simple steps and easy ingredients
Begin with the shortbread base: whisk together all-purpose flour, granulated sugar, corn starch, and a pinch of salt. Stir in melted unsalted butter until a thick dough forms. Press the dough into a lined 9×13-inch pan, creating a small lip around the edges, and bake for about 20–25 minutes. The corn starch in the crust helps keep it tender, while salt balances the overall flavor. 
While the base bakes, prepare the lemon layer by whisking together granulated sugar and corn starch to remove lumps, then whisk in eggs and freshly squeezed lemon juice. When the base comes out of the oven, gently prick the very top of the shortbread with a fork — only pierce the surface to help the lemon mixture adhere and avoid it seeping under the crust. Pour the lemon mixture over the warm base and return the pan to the oven to bake for another 20–25 minutes, until the top looks set and no longer wobbles.
About Corn Starch: Corn starch is the preferred thickener for the lemon layer because it has greater thickening power than flour and helps the filling set firmly. Do not omit it.
Fresh Lemon Juice: This recipe calls for 1 cup (about 240 ml) of freshly squeezed lemon juice. Small lemons yield about 3 tablespoons each, while larger lemons can give up to 4 tablespoons. Plan to buy roughly 5–6 small lemons or 4–5 medium-to-large lemons.
After baking, allow the bars to cool, then chill so the lemon layer firms completely. A light dusting of powdered sugar or a dollop of whipped cream makes a lovely finishing touch. 
Baking Tips & Tricks
- Use freshly squeezed lemon juice; bottled juice is often too sharp for baking.
- Prick the top of the baked crust lightly with a fork so the lemon layer adheres and doesn’t run underneath.
- When finished baking, the lemon layer should appear set and should not wobble when you nudge the pan. Baking times are approximate and depend on your oven.
- Cool completely: allow the pan to sit at room temperature for about 1 hour, then refrigerate 2–3 hours before slicing so the filling firms for clean cuts.
More Lemon Recipes to Love:
- Lemon Bundt Cake
- Lemon Blueberry Cake
- Lemon Cupcakes
Lemon Bars
Equipment
- 9×13 inch (23 x 33 cm) baking pan*
Ingredients
Shortbread Base
- 2 1/4 cup all-purpose flour
- 1/2 cup granulated sugar
- 1 tablespoon corn starch
- 1/4 teaspoon salt
- 1 cup unsalted butter, melted
Lemon Layer
- 2 cups granulated sugar
- 1/3 cup corn starch
- 6 large eggs
- 1 cup lemon juice*, freshly squeezed
Instructions
- Preheat the oven to 325°F (160°C). Line a 9×13 inch pan with parchment paper, leaving an overhang for easy lifting.
Shortbread Base
- In a large bowl whisk together the flour, sugar, corn starch and salt.
- Stir in the melted butter until a thick dough forms.
- Press the dough into the bottom of the lined pan and form a small lip around the edges.
- Bake for 20–25 minutes, or until the base looks set and begins to turn golden around the edges. Remove from the oven but keep the oven on.
Lemon Layer
- Whisk together the sugar and corn starch to remove any lumps.
- Whisk in the eggs, then whisk in the freshly squeezed lemon juice until smooth.
- When the base is done, gently prick the top surface with a fork (only pierce the surface).
- Pour the lemon filling evenly over the hot base and bake at 325°F for 20–25 minutes, until the top looks set and no longer wobbles when nudged.
- Remove from the oven and let the pan cool at room temperature for about 1 hour, then chill in the refrigerator for at least 2 hours to firm the filling.
- Lift the bars from the pan using the parchment overhang, place on a cutting board, and slice with a sharp knife. Optionally dust with powdered sugar before serving.
Notes
- To make a smaller batch, halve the recipe and bake in an 8×8 inch pan. Expect roughly 20 minutes for each baking stage.
- Store bars in an airtight container in the refrigerator for up to 5 days. To freeze, wrap tightly and freeze up to 2 months; thaw in the fridge.
- Always use freshly squeezed lemon juice — bottled juice is too acidic for this recipe. You’ll need about 5–6 small lemons or 4–5 large lemons to yield 1 cup juice.
- Nutrition information is an estimate and assumes 18 equal portions.