Lemon Bars

Michael Eisenwasser

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A buttery shortbread crust under a tart lemon curd filling, dusted with powdered sugar and cut into 16 squares.

Prep 20 min

Cook 35 min

Serves 16

Gluten-free

Ingredients

Shortbread Crust

• 1 cup (225 g) unsalted butter, melted and slightly cooled
• 1/2 cup (60 g) powdered sugar
• 1 teaspoon pure vanilla extract
• 1/2 teaspoon fine salt
• 2 cups (280 g) gluten-free flour blend

Lemon Filling

• 2 cups (400 g) granulated white sugar
• 1/3 cup (47 g) gluten-free flour blend
• 6 large eggs, room temperature
• 1 cup (240 ml) fresh lemon juice (from about 5 to 6 lemons)
• 2 tablespoons finely grated lemon zest
• Pinch of fine salt

To Finish

• 2 tablespoons powdered sugar, for dusting
• Optional: 30 g dark chocolate (at least 60% cacao, no inulin or polyols), melted, for drizzling

Makes 16 bars in a 9x13-inch pan. One serving is 1 bar.

Instructions

Bake the Crust

1. Heat the oven to 350°F (175°C). Line a 9x13-inch pan with parchment, leaving an overhang on two sides for lifting.
2. Whisk the melted butter, powdered sugar, vanilla, and salt in a medium bowl until smooth.
3. Add the flour blend and stir with a spatula until a soft, evenly moistened dough forms.
4. Press the dough into an even layer across the bottom of the pan. A flat-bottomed measuring cup helps smooth the surface.
5. Bake on the middle rack for 18 to 22 minutes, until the edges are just turning golden. The center should look set but pale. Leave the oven on.

Make the Filling

1. While the crust bakes, whisk the granulated sugar and flour blend together in a large bowl.
2. Add the eggs and whisk until fully combined and slightly foamy.
3. Whisk in the lemon juice, lemon zest, and salt. The mixture will look thin; that's correct.
4. Strain the filling through a fine-mesh sieve into a large measuring cup or pitcher. This catches any stray zest threads and egg bits for a smoother top.

Bake the Bars

1. Pour the strained filling over the hot crust as soon as it comes out of the oven. Pouring onto a warm crust helps the filling start setting from below.
2. Return the pan to the oven and bake for 22 to 28 minutes, until the center is just set and no longer jiggles when you tap the pan. A slight wobble is fine; it will firm up as it cools.
3. Cool the pan on a rack for 1 hour at room temperature, then refrigerate for at least 2 hours (or overnight) before cutting. Cold bars cut cleaner than warm ones.

Finish

1. Lift the slab out of the pan using the parchment overhang. Trim 1/4 inch off each edge for a cleaner look (optional), then cut into a 4x4 grid for 16 bars.
2. Dust the tops with powdered sugar just before serving. If dusting ahead, the sugar will dissolve into the filling within an hour; re-dust at serving time.
3. For the optional chocolate drizzle, melt 30 g of dark chocolate and drizzle lightly across the full pan with a fork or spoon. That's under 2 g of chocolate per bar.

Tips & Substitutions

• Zest before you juice. Microplane the lemons first while they're firm, then juice them. Zesting a half-squeezed lemon is a frustrating exercise.
• Roll the lemons. Firmly rolling whole lemons on the counter for 10 seconds before juicing breaks down the juice sacs and doubles the yield. A medium lemon should give 3 tablespoons of juice; a large Meyer or Eureka can hit 4.
• Meyer lemons work. Meyer lemons are low-FODMAP and a touch sweeter and less tart than standard lemons. Use them 1:1 if you want a mellower bar, or split half-and-half with regular lemons.
• Bottled lemon juice in a pinch. Works, but the flavor is noticeably flatter. If you use bottled, keep the zest from a fresh lemon for aroma; most of what reads as "lemon" in a bar is the zest oil, not the juice.
• Dairy-free version. A 1:1 vegan butter stick (Miyoko's, Earth Balance soy-free) swaps in for the butter with no other changes. The crust will be slightly softer but still holds a clean cut.
• Lime or yuzu variation. Both limes and yuzu are low-FODMAP; sub 1:1 by volume for the lemon juice and zest. Yuzu is harder to find fresh in the US but bottled yuzu juice (check label for just juice, no added honey or inulin) works.
• Don't overbake the filling. The center should just be set, not browned. A golden skin on top is normal, but if the whole surface turns brown, the eggs have overcooked and the texture will be grainy.
• If the top cracks, it usually means the oven runs hot or the bars baked a few minutes too long. Dust heavily with powdered sugar to hide it, or skip the dusting and drizzle with melted dark chocolate.

Why This Works

Lemon juice and zest are low-FODMAP at typical serves. Monash tests both as low-FODMAP at normal recipe amounts with no low-FODMAP serve limit flagged. The 1 cup of juice and 2 tablespoons of zest in this recipe don't push the bars over any threshold. Acidic foods can still be a non-FODMAP trigger for some people with reflux or IBS, so if citrus bothers you, cut the bars smaller or skip the extra zest.

Butter math. Butter is low-FODMAP at 1 tablespoon per serve because it's almost pure fat. One cup across 16 bars is about 1 tablespoon per bar, right at the serve. If you share two bars in a sitting, use the vegan butter swap or cut smaller squares.

Sugar isn't a FODMAP. White granulated sugar is sucrose: one glucose plus one fructose in a 1:1 ratio. The small intestine absorbs sucrose fully, so the 2 cups in the filling and 1/2 cup in the crust carry no FODMAP load split across 16 bars. Powdered sugar is the same sucrose with a bit of cornstarch.

Eggs are free. Eggs have no FODMAPs at any serve, so the 6 eggs in the filling are purely structural. They set the custard without contributing to the overall load.

Gluten-free flour blend holds the crust. The gluten-free flour blend already includes xanthan gum, so the shortbread binds without extra starch. Rice flour and starches give the crust a crisp, sandy texture without wheat's fructans. The small amount of blend in the filling (1/3 cup) thickens the custard the same way a wheat-flour version would.

No honey, no agave, no HFCS. Most traditional lemon bar recipes use only sugar, eggs, butter, flour, and lemon, so there's nothing high-FODMAP to strip out. If you see a recipe with honey or agave in the filling, skip it; both are high in fructose and would push a single bar over the limit.

Optional dark chocolate drizzle within serve. Monash tests dark chocolate as low-FODMAP at 30 g per serve. Drizzling 30 g across the full pan is under 2 g per bar, well below the threshold, and adds a chocolate finish against the tart lemon.

Storage

Store cooled, cut bars in an airtight container in the fridge for up to 5 days. Layer with parchment between rows to keep the tops from sticking. For longer storage, freeze undusted bars individually wrapped in plastic, then in a zip-top bag, for up to 2 months. Thaw in the fridge overnight and dust with fresh powdered sugar before serving. Don't leave lemon bars at room temperature for more than 2 hours at a time; the egg custard filling is perishable.

Not sure about an ingredient? FODMAP Tracker includes a database of 1,000+ foods with FODMAP ratings to help you cook with confidence.