Rhubarb and custard blondies

These fun rhubarb and custard blondies will keep you coming back for more! Delicious, buttery squares topped with rhubarb compote, custard and white chocolate drizzle.

They are soft and gooey in the middle, with crispy and chewy edges. Perfect treat to share with your friends and family! The recipe comes together super quick and you don't even need any special equipment to make them!

Jump to:

• Why you will love this recipe
• Key ingredients and substitutions
• How to make these blondies
• Storing
• FAQs
• 📖 Recipe
• 💬 Comments

Why you will love this recipe

Firstly, the combination of rhubarb and custard is simply delicious. Different flavours and contrasting textures of these two are a true excitement for the taste buds. Tart and tender rhubarb plus sweet, velvety- smooth custard are just perfect together. There has been many combinations of these two ingredients in desserts over the years, but this one, by far, is my favourite.

These dense, fudgy and gooey little squares are just perfect for whenever you need a quick fix of something sweet, but don't fancy baking a cake or anything too complicated.

Key ingredients and substitutions

These rhubarb and custard blondies are made using pantry staples, and most of them are more likely in your kitchen cupboard already. Let's have a look at some of the key ingredients:

Rhubarb - I like to use fresh rhubarb, but frozen or canned rhubarb will also work. If you are using canned rhubarb, make sure to drain it first. Whichever type of rhubarb you decide to use, it almost always needs some sugar added to it, to reduce its tartness. You may not need the whole amount that the recipe calls for, but any leftovers can be stored in the fridge and used to top up your porridge, yogurt or pancakes.

Custard - The recipe calls for two types of custard: powdered and ready-made. Powdered custard is used in the cake batter, to replace part of flour and create that delicious, buttery taste. Ready-made custard is used on top, along with rhubarb. But you can use only powdered custard in the whole recipe. See the recipe notes for instructions.

White chocolate - You will need about 200 g of white chocolate in total. I normally use bar of chocolate and chop it into small chunks. That said, you can use chocolate buttons, chips or wafers.

Sugar - There are two different types of sugar in this recipe, caster (or regular white) and soft light brown sugar. Technically, you can stick just to caster / granulated white sugar, but I like to mix both types into the batter. Brown sugar adds that delicious, mellow, almost caramel-like taste to bakes and helps to keep the texture of blondies nice and soft.

Eggs - I have tested this recipe with 3 medium eggs, or two large eggs, and in both cases, it worked fine. Feel free to use whichever type you have available.

How to make these blondies

If you would like, watch this Instagram Reel to see how easy it is to make these blondies!

Start by prepping your rhubarb and custard topping. If you are using fresh rhubarb, cut it into smaller chunks (roughly about 2- 3 cm long) and place it in a wide saucepan with caster sugar and 2 tablespoon of water. Cook it until it starts to break up and becomes jammy. If you'd like, you can add few drops of pink food colouring to intensify the colour of the compote.

If you are using powdered custard only in this recipe, prepare the custard topping at this stage. You will need about 5 tablespoon of custard for the topping in total.

Alternatively, if you don't fancy cooking and stewing the rhubarb first, you may want to check out the recipe for Rhubarb and White Chocolate Blondies from Hummingbird High ,where whole chunks of rhubarb are used on top.

To make blondies batter, start by melting butter and both sugars together until you have thick mixture that is smooth and glossy. Allow the mixture to cool before adding eggs into it.

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Next, mix in the dry ingredients: flour, custard powder and baking powder. Add them to the cooled butter mix and stir until combined. Pour in the vanilla and fold in the white chocolate, before pouring the mix into baking tin.

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Add dollops of rhubarb compote and custard on top of the batter, and use a cocktail stick or a toothpick to create the marble pattern with it.

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If you are using 8 x 8 inch baking tin, bake them for 45-50 minutes or until the edges are coming away from the tin and the mixture is set. For fudgy and gooey blondies, toothpick inserted in the middle should not be dry and should have some crumb attached to it. Just like with my homemade brownies ,these blondies will continue to cook and set as they cool.

If you prefer more cakey texture, bake them for 5-10 minutes longer.

I also baked these in rectangular, 20cm x 30cm (8' x 12') baking pan. As it is shallower and has larger surface, baking time will differ. For fudgy and gooey texture, you will bake them for about 35- 40 minutes. Add another 5-10 minutes for more cakey texture.

If your bake starts catching a bit of colour too quickly, cover it with some kitchen foil. Remove baked blondies from the oven, let them cool down in the tin, and drizzle with some melted white chocolate (optional). Transfer your baked blondies to the fridge for minimum of 2 hours, or overnight.

Just like good brownies need time to set properly, these blondies will also require some time to cool down, firm up and set. If you try slicing them while they are still hot, the bake will more likely fall apart. So it's important to allow them at least good couple of hours in the fridge.

Storing

You can store these in the airtight container for up to 3-4 days. The blondies will also freeze well. Make sure to wrap each slice well, then transfer to freezer-friendly container. freeze the individual Defrost them overnight in the fridge.

FAQs

I don't like rhubarb, can I use anything else instead?

You can replace rhubarb with some other fruits like strawberries, cranberries, quinces, raspberries or sour cherries. You want to use something that is a bit tart and sharp in flavour, balanced with bitterness and sweetness. Favourite jam could also be used in place of rhubarb.

Alternatively, you may want to try some of my other blondie recipes, like these Chocolate Chip Walnut Blondies or readers favourite Biscoff White Chocolate Blondies.

Can I use different size baking tin?

Yes you can. Just remember that baking times will vary for different sizes. I tested this recipe in 8'x 8' square baking tin, 8' x 12' rectangular tin, and 9' round baking tin.

Why my blondies look under-baked?

Blondies, just like brownies should be taken out of the oven, when they are still slightly under-baked. This is because they will continue to cook and set after you take them out of the oven. That is what gives them fudgy and gooey texture. If you prefer yours to be more cake-like, then simply add few more minutes to the baking time.

Help, my blondies are not fudgy and really dry!

You have over-baked your blondies. Next time, simply reduce the baking time and perform the toothpick test to make sure it comes out with some crumb attached to it.

Make sure to tag me on Instagram if you try this, or any other of my recipes. Feel free to to also leave me a comment and a rating of the recipe below.

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This post was originally published in February 2020. It has been updated with new photos and tips in June 2021.