The Best Rhubarb Custard Bars You’ll Ever Bake

There’s something magical about rhubarb custard bars. I remember biting into one for the first time as a child, standing barefoot in my grandmother’s sunny kitchen while she cut the bars into neat squares. The tang of the rhubarb, the creamy custard layer, and the buttery shortbread crust, it was unlike anything else. It was the flavor of spring wrapped in nostalgia.

Rhubarb custard bars are the ultimate spring and summer treat. They’re perfect for bake sales, brunches, picnics, or whenever you want to spotlight rhubarb’s tart charm. This recipe is easy enough for a weeknight baking session but elegant enough to impress guests at any gathering. Best of all, it uses fresh rhubarb, and the custard filling makes every bite rich, creamy, and satisfying. If you’re a fan of fruity, buttery desserts with a hint of nostalgia, these rhubarb custard bars will quickly become a favorite.

Why I Always Crave These Rhubarb Custard Bars

What sets these rhubarb custard bars apart is the harmony of layers. First, there’s a tender, buttery shortbread crust that provides the perfect foundation, crisp at the edges and melt-in-your-mouth soft in the center. On top of that rests the real star: a luscious custard packed with chopped rhubarb. The custard bakes to creamy perfection, and the rhubarb softens just enough to release its signature tang while keeping its texture.

Another reason I love this recipe is the balance of flavor. Rhubarb can be tart, sometimes overwhelmingly so, but paired with the sweet, silky custard and that golden crust, it becomes a treat that sings.

Customization is easy here too. Want it less sweet? Reduce the sugar in the custard layer. Prefer a gluten-free version? You can swap the crust for one made with almond or oat flour. Lactose intolerant? Use coconut milk and a dairy-free butter alternative, it still turns out dreamy.

Unlike many rhubarb desserts that rely on strawberries for sweetness, this one lets the rhubarb shine all on its own, making it ideal for true rhubarb lovers. It’s also a fantastic way to use up a bumper crop or those few extra stalks from the farmer’s market.

With minimal prep, pantry-friendly ingredients, and a one-bowl custard layer, this recipe delivers maximum payoff with little effort. And that’s why I return to these rhubarb custard bars every spring, they never let me down.

Recipe Card

Get Perfect Rhubarb Custard Bars Every Time

Baking rhubarb custard bars is pretty straightforward, but a few smart tips can take them from good to unforgettable. Here’s what I’ve learned after making this recipe dozens of times:

1. Use fresh rhubarb when possible: While frozen rhubarb works in a pinch, fresh rhubarb delivers the best flavor and texture. If using frozen, thaw completely and drain excess liquid—too much moisture can make your custard runny.

2. Chill the crust before baking: Once you press the shortbread crust into the pan, pop it in the fridge for 10–15 minutes before blind baking. This step helps it stay crisp and prevents shrinking.

3. Bake the crust first: This is crucial. Pre-baking the crust (aka blind baking) for about 12–15 minutes ensures it doesn’t turn soggy when the custard is added. You want that buttery base to hold its texture.

4. Don’t overbake the custard: The custard should be just set, slightly jiggly in the center when you remove it from the oven. It will firm up as it cools. Overbaking can result in a rubbery texture instead of the silky smooth finish we want.

5. Let it cool completely: These bars slice best when fully chilled. I like to refrigerate them for at least two hours before cutting. Use a sharp knife and wipe between slices for clean edges.

Tasty Variations to Try

1. Strawberry Rhubarb Custard Bars

If you’re looking to balance rhubarb’s tartness with something naturally sweet, strawberries are your best friend. Swap out half of the rhubarb for chopped fresh strawberries. The fruit combo gives the custard a gorgeous pink hue and that classic springtime flavor. Perfect for garden parties or brunch spreads.

2. Lemon Rhubarb Custard Bars

Amp up the tang by adding lemon zest and a tablespoon of lemon juice to the custard filling. The citrus complements the rhubarb beautifully and gives the bars a bright, zippy edge. I often serve these at tea time with a dusting of powdered sugar on top—pure elegance!

3. Raspberry Rhubarb Bars

Raspberries offer a deeper berry flavor with a lovely ruby-red color. Mix 1 cup of raspberries with your chopped rhubarb and stir them gently into the custard. You get a rich, sweet-tart balance that’s visually stunning and a bit more complex.

4. Gluten-Free Rhubarb Custard Bars

Need a gluten-free version? Just substitute the flour in the crust with a gluten-free 1:1 baking flour blend. Make sure the blend includes xanthan gum or a similar binder for structure. The result is just as buttery and crumbly, no one will guess it’s gluten-free.

Wrapping It Up

There’s something truly special about rhubarb custard bars. They bring together contrast in the most delightful way, tangy rhubarb against creamy custard, a crumbly buttery crust beneath a soft, melt-in-your-mouth top. It’s the kind of recipe that feels both nostalgic and fresh, rustic yet elegant.

Personally, I’ve made this recipe more times than I can count, and it never lasts long in my kitchen. It’s always the first thing to disappear at dessert tables, with guests asking, “Wait, what’s in this?!” That bright tartness from the rhubarb, softened by the sweet custard, is a combination that keeps everyone coming back for seconds.

If you loved this, you might also enjoy my Rhubarb Custard Pie or Chess Squares Bars, two more springtime treats that showcase fruit at its best.

FAQs about Rhubarb Custard Bars

So go ahead, bake a batch, let them chill, and enjoy a slice of sunshine with every bite.