Rhubarb White Chocolate Elderflower Tart

My neighbor showed up one May morning with an armful of rhubarb stalks, pink and green and impossibly fresh. I'd been eyeing a white chocolate custard recipe for weeks but hadn't found the right occasion. She mentioned elderflower was blooming down by the creek, and suddenly the whole tart came together in my head before I'd even put the kettle on. That afternoon, my kitchen smelled like spring itself.

I first served this at a garden party where half the guests were skeptical about rhubarb desserts. By the time I sliced into the tart, revealing that pale custard beneath the rosy fruit, the conversation had shifted entirely to recipe requests. One friend admitted she'd only ever had rhubarb in crumbles and hadn't realized it could taste this elegant. I still get texts every spring asking if I'm making it again.

Ingredients

• All-purpose flour: Forms the foundation of a tender, buttery crust that holds up to the creamy filling without going soggy.
• Cold unsalted butter: Cubed and kept cold, it creates flaky layers in the pastry when it melts in the oven.
• Powdered sugar: Dissolves more easily than granulated, giving the crust a delicate sweetness and softer crumb.
• Egg yolk: Binds the dough together and adds richness without making it tough.
• White chocolate: Choose good quality with cocoa butter listed first for a smooth, creamy custard that sets beautifully.
• Heavy cream and whole milk: The combination gives body and richness without making the custard too heavy.
• Elderflower cordial: This is the secret ingredient that ties everything together with its honeyed, floral notes.
• Egg yolks: Thicken the custard and give it a luscious, velvety texture.
• Rhubarb: Look for firm stalks with bright color and trim away any leaves, which are toxic.
• Lemon zest: Brightens the rhubarb and keeps it from tasting flat or one-dimensional.

Instructions

Mix the pastry:

Pulse the flour, cold butter cubes, powdered sugar, and salt in your food processor until it looks like coarse sand with a few pea-sized lumps. Add the egg yolk and a tablespoon of cold water, pulsing just until the dough starts clumping together.

Chill and roll:

Pat the dough into a flat disk, wrap it tightly, and let it rest in the fridge for 30 minutes so the gluten relaxes. Roll it out on a floured counter until it's large enough to drape over your tart tin with a little overhang.

Blind bake the crust:

Press the dough gently into every corner of the tin, trim the edges, then chill again for 15 minutes to prevent shrinking. Line with parchment, fill with baking beans, and bake at 180°C until the edges are set, then remove the beans and bake until golden.

Make the custard base:

Warm the cream and milk in a saucepan until you see steam rising, but don't let it boil. Whisk your egg yolks with sugar and vanilla until they turn pale and slightly thick.

Temper and thicken:

Pour the hot cream slowly into the yolks while whisking constantly so they don't scramble. Return everything to the pan and stir over low heat until the mixture coats the back of a spoon.

Finish the custard:

Take the pan off the heat and stir in the chopped white chocolate and elderflower cordial until completely smooth. Pour this into your cooled tart shell and refrigerate for at least an hour.

Roast the rhubarb:

Lay the rhubarb batons in a single layer in a baking dish, sprinkle with sugar and lemon zest, then drizzle with elderflower cordial. Cover with foil and roast at 190°C until tender but still holding its shape.

Assemble and chill:

Once the rhubarb has cooled completely, arrange the pieces over the set custard in whatever pattern makes you happy. A light brush of extra cordial adds shine and a hint more flavor.

Save

The first time I brought this tart to a potluck, someone asked if I'd bought it from a patisserie. I laughed and admitted I'd nearly panicked when the custard looked too loose, but it had set perfectly by the time we gathered. That tart became the thing people remembered long after the evening ended, and I realized that sometimes a dish can carry a whole occasion on its back.

Choosing Your Rhubarb

Look for stalks that are firm and snap cleanly when you bend them. The color ranges from pale green to deep crimson depending on variety, but color doesn't affect flavor as much as you'd think. Thinner stalks are often more tender, though thicker ones work beautifully when roasted. Always trim away the leaves completely and wash the stalks before cutting them into even pieces.

Make-Ahead Magic

This tart is at its best when each element has time to settle and chill. I often bake the crust and roast the rhubarb the night before, then make the custard the next morning and let it set while I do other things. You can assemble the whole tart up to four hours before serving and keep it chilled. Just remember that the rhubarb softens over time, so if you're making it a full day ahead, add the fruit only a few hours before guests arrive.

Serving and Storing

Let the tart sit at room temperature for about 10 minutes before slicing so the custard isn't too firm. A sharp, thin knife dipped in hot water makes clean cuts. Leftovers keep well in the fridge for up to two days, covered loosely with plastic wrap.

• Serve with a small dollop of lightly whipped cream or crème fraîche if you want extra richness.
• A few toasted pistachios or slivered almonds add a lovely crunch on top.
• Pair it with a chilled glass of Moscato or a homemade elderflower spritz for a perfect spring dessert.

Save

Every time I make this tart, I'm reminded that the best recipes are the ones that taste like a specific moment, a season, a fleeting combination of flavors you only get once a year. I hope this one finds a place in your spring traditions.

Recipe FAQs

→ Can I make this tart in advance?

Yes, this tart is perfect for making ahead. Prepare the entire tart up to 24 hours in advance and keep it chilled. Add the rhubarb topping a few hours before serving for best presentation.

→ What can I substitute for elderflower cordial?

If elderflower cordial is unavailable, use a light floral syrup like rose or lavender, or substitute with a mix of lemon juice and honey for a different but delicious flavor profile.

→ How do I prevent the tart crust from becoming soggy?

Blind baking the crust thoroughly until golden is essential. Ensure the crust is completely cooled before adding the custard, and the custard should be set firmly in the refrigerator before topping with rhubarb.

→ Can I use frozen rhubarb instead of fresh?

Fresh rhubarb works best for this tart as it holds its shape better when roasted. If using frozen, thaw and pat dry thoroughly first, and reduce roasting time slightly to prevent it from becoming too soft.

→ What type of white chocolate should I use?

Choose a good quality white chocolate with at least 30% cocoa butter for the best flavor and smooth melting. Avoid baking chips as they contain stabilizers that may affect the custard texture.

→ How should I store leftover tart?

Cover the tart loosely with plastic wrap and refrigerate for up to 3 days. The rhubarb may soften slightly over time, but the flavor remains excellent. Serve chilled directly from the refrigerator.