Lemon Bars

Low FODMAP lemon bars with a butter and gluten-free flour shortbread crust under a fresh lemon, egg, and sugar filling.

Prep 20 min

Cook 45 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 edges are set and the center has only a slight wobble with no liquid ripple. It firms 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. A medium lemon gives about 3 tablespoons of juice; rolling it on the counter first makes it easier to squeeze.
• Meyer lemons work. Meyer lemons are low FODMAP and a little sweeter than standard lemons. Use them 1:1, or split half-and-half with regular lemons.
• Lime or yuzu variation. Both are low FODMAP; swap 1:1 by volume for the lemon juice and zest. For bottled yuzu, check the label for plain juice with no added honey or inulin.
• Bottled lemon juice in a pinch. It works, but the flavor is flatter. Keep the zest from a fresh lemon, since most of the lemon flavor in a bar comes from the zest.
• Dairy-free version. A 1:1 vegan butter stick works in the crust; check the label for cashews, inulin, and chicory root. The crust will be slightly softer but still cuts cleanly.
• Don't overbake the filling. Pull the pan when the edges are set and the center has a slight wobble but no liquid ripple. If the whole surface browns, the eggs have overcooked and the texture turns grainy.

Why This Works

Lemon. Lemon juice and zest are low FODMAP at recipe amounts. Each bar has about 1 tablespoon of juice and a little zest.

Butter. Butter is mostly fat with very little lactose. One cup across 16 bars is about 1 tablespoon per bar.

Plain sugar and eggs. White sugar, powdered sugar, and eggs are low FODMAP at the amounts used here, so the filling needs nothing stripped out. Some lemon bar recipes add honey, which is low only at about 1 teaspoon per serving.

Gluten-free crust. The gluten-free flour blend already includes xanthan gum, so the shortbread base binds without wheat. The optional dark chocolate drizzle is under 2 g per bar, well below the 30 g low FODMAP serve.

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.