Old-Fashioned Lemon Rhubarb Shortbread with Lemon Glaze

Published: June 5, 2026

Old-Fashioned Lemon Rhubarb Shortbread with Lemon Glaze is a thick, buttery dessert bar packed with juicy pink rhubarb pieces and bright lemon flavor. The shortbread base is rich and tender, while the lemon glaze adds a sweet-tart finish that makes every bite feel extra special. Make these when you want a spring or summer dessert that looks beautiful, slices neatly, and tastes like pure comfort. Similar lemon-rhubarb bar desserts are known for their buttery crusts and tangy fruit filling, which makes this combination especially fitting for seasonal baking.

Ingredients & Substitutions

All-purpose flour: Gives the shortbread its structure and soft crumb. A 1:1 gluten-free flour blend can be used if needed.
Powdered sugar: Sweetens the shortbread and helps create a tender texture. It is also used in the glaze for a smooth finish.
Salt: Balances the sweetness and makes the lemon flavor stand out.
Baking powder: Helps the shortbread rise slightly and keeps it from feeling too dense.
Unsalted butter: Creates the rich, buttery base that makes the bars so tender. Use high-quality butter for the best flavor.
Egg: Helps bind the dough and gives the shortbread a softer, more cake-like bite.
Lemon zest: Adds a bright citrus aroma and a stronger lemon flavor throughout the bars.
Fresh lemon juice: Gives the dough and glaze a tangy lift. Fresh is best for the brightest flavor.
Vanilla extract: Rounds out the flavor and softens the sharpness of the lemon.
Fresh rhubarb: Adds tart flavor and little bursts of pink color. Frozen rhubarb can work if thawed and drained well.
Powdered sugar for glaze: Creates a smooth, pourable lemon icing.
Extra lemon juice for glaze: Loosens the glaze to the right consistency.
Extra lemon zest for glaze: Adds more citrus flavor and makes the topping taste fresh.

Tips for Success

Dice the rhubarb very small: Smaller pieces bake more evenly and give each bar a better balance of fruit and shortbread.
Do not overmix the dough: Mix just until the flour disappears so the shortbread stays tender instead of tough.
Press the dough evenly into the pan: An even layer helps the bars bake uniformly and makes slicing easier later.
Watch the bake time carefully: The bars should be set and lightly golden at the edges, but not dry.
Glaze while the bars are slightly warm: This helps the lemon glaze spread smoothly over the surface.
Let the glaze set before cutting: Waiting a little while keeps the bars neat and prevents the glaze from smearing.
Serve at room temperature: The texture and lemon flavor are best once the bars have softened slightly after chilling.

How to Make Old-Fashioned Lemon Rhubarb Shortbread with Lemon Glaze

These bars come together with a simple shortbread batter, fresh rhubarb, and a quick lemon glaze.

Preheat the oven to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper, leaving an overhang on the sides.
Mix the butter and sugar in a large bowl until light and creamy.
Add the egg, lemon zest, lemon juice, and vanilla extract and mix until smooth.
Fold in the dry ingredients by adding the flour, salt, and baking powder. Mix just until combined.
Gently fold in the rhubarb so it is evenly distributed throughout the dough.
Press the dough into the pan using lightly floured hands or the back of a spoon. Smooth it as evenly as possible.
Bake for 28 to 32 minutes, until the edges are golden and the center is just set.
Cool in the pan for about 20 minutes.
Make the glaze by whisking together powdered sugar, lemon juice, and lemon zest until smooth and pourable.
Drizzle the glaze over the warm bars and spread it evenly with the back of a spoon.
Let the glaze set for 15 to 20 minutes, then lift the bars out using the parchment and cut into squares.

How to Use Old-Fashioned Lemon Rhubarb Shortbread

These bars are easy to serve for both casual and special occasions.

Serve them as a spring dessert with tea or coffee.
Pack them for picnics, brunches, or bake sales.
Add them to a dessert tray with fruit bars and cookies.
Serve them at room temperature for the best texture.
Pair them with or for a bright citrus-rhubarb spread.

How to Store Old-Fashioned Lemon Rhubarb Shortbread

Store the bars in an airtight container at room temperature for up to 4 days. They stay soft and flavorful, and the lemon glaze keeps them tasting fresh and bright.

For longer storage, refrigerate the bars for up to 1 week or freeze them for up to 2 months. If freezing, separate layers with parchment paper and thaw at room temperature before serving.

FAQs

What do lemon rhubarb shortbread bars taste like?

They taste buttery, tangy, and lightly sweet, with soft bites of rhubarb and a bright lemon glaze. The shortbread base adds richness that balances the fruit perfectly.

Can I make these ahead of time?

Yes, these bars are great for making ahead. They keep well for several days, which makes them ideal for gatherings and meal prep.

Can I use frozen rhubarb?

Yes, frozen rhubarb can be used. Thaw it first and drain off extra liquid so the bars do not become too wet.

How do I keep the shortbread from becoming tough?

Do not overmix the dough once the flour is added. Mix only until combined and press it gently into the pan.

Can I add more lemon flavor?

Yes, you can add extra zest to both the dough and the glaze. A second glaze layer after the first sets will make the lemon flavor even stronger.

Can I serve these warm?

Yes, but they are best once slightly cooled and set. Warm bars will be softer, while room-temperature bars slice more cleanly.