Rhubarb custard bars are a lovely spring treat! With shortbread crust and rich custard they’re a great way to use up rhubarb from the garden.
Photography by Kelly Neil
With such a short growing season, rhubarb is a special spring treat. With a sturdy shortbread crust and rich, egg-based custard, baking these rhubarb custard bars is a terrific way to use rhubarb from the garden.
This is an old-fashioned dessert that’s pretty simple to make, and in one bowl to boot (we kind of love one bowl recipes). It may seem like the bars contain a lot of sugar but you really do need it to take the edge off of the rhubarb’s tartness. They’re a simple, rustic dessert (you really can’t mess it up) but make sure to leave yourself some time as the bars must cool for a few hours before slicing.
Use the JUMP TO RECIPE button at the top, or scroll to the bottom of the post to see the printable recipe card with full ingredient measurements and complete instructions.
Recommended Tools
- Oven thermometer—we can’t recommend this enough!
- 8 or 9-inch (20 or 23-cm) square baking dish
- Large mixing bowl
- Hand or stand mixer
- Measuring cups and spoons or a digital kitchen scale
- Rubber spatula or wooden spoon
- Parchment paper
- Wire cooling rack
Ingredients
- Butter: Salted butter is what we use for this recipe.
- Eggs: We use large eggs in all of our recipes.
- Rhubarb: You can use fresh or frozen rhubarb.
Keep scrolling to see clear and detailed process shots, as well as tips and notes to help you make Rhubarb Custard Bars perfectly the first time!
Method
TOP TIPS
1. Peel the Rhubarb. If your rhubarb is older or the stalks are really thick, peel them for the best taste.
2. Cool Before Slicing. The bars need to be fully cool before cutting into squares because the custard is too soft when it’s still warm.
3. Eat Fresh. Custard bars don’t freeze well as a general rule, so plan to make these when you can eat the whole batch in a day or two.
Recipe Notes
- Don’t worry if your custard turns light gold in places while baking—this is normal!
- Frozen rhubarb will work here, however, you may need to bake the bars a bit longer.
- It’s pretty important to let the bars cool before slicing because the custard needs time to set.
How to Store and Freeze Rhubarb Bars
- To Store: Place the sliced bars in an airtight container and store at room temperature for the first day. After that, store the container in the fridge. Baked custard doesn’t store fabulously, and can make the shortbread soggy.
- To Freeze: These bars don’t freeze well so eat them within a couple of days.
Substitutions & Variations
- If you want your bars a bit sweeter, replace half of the rhubarb with sliced strawberries. Please note, strawberries contain more water than rhubarb so the custard may take longer to set in the oven.
- For extra flavour, add lemon zest, orange zest, or a teaspoon of finely chopped fresh ginger to the custard if you like.
- To make this recipe dairy-free, use a good quality vegan butter.
- To make gluten-free rhubarb custard bars, sub a good GF flour blend (like the Bob’s Red Mill one) for the all-purpose flour. There are probably other flours that will work as a shortbread base since it doesn’t need to rise, but we haven’t tested any.
FAQ
The simple answer is no, you don’t. That being said, if your rhubarb is older, tough, and woody, peeling the outside with a vegetable peeler will leave behind the more tender inside of the stalks.
We bake the shortbread crust first until golden, about 24 minutes because we like a slightly crisp snap to the crust. We bake the crust with the custard topping for 42 to 45 minutes. Baking time depends on your oven (we recommend using an oven thermometer!), and whether or not you are using fresh or frozen rhubarb.
These bars are best eaten fresh, however, it isn’t always possible to eat them all in one day. We recommend placing them in a container in the fridge after the first day to keep the crust from getting too soggy.
We haven’t tried freezing the bars. This is because freezing can sometimes change the taste and texture of custard. However, just because we haven’t tried it doesn’t mean you can’t.
More Rhubarb Recipes
Rhubarb Scones with Fresh Ginger
Rhubarb Upside-Down Cake
Apple Rhubarb Pie
Rhubarb Clafoutis
Gluten-Free Rhubarb Crisp
Recipe
Rhubarb Custard Bars (One Bowl)
Description
Equipment
- Oven thermometer we can't recommend this enough for all of your baking!
- 8 or 9-inch (20 or 23-cm) square baking dish
- Large mixing bowl
- Hand or stand mixer
- Measuring cups and spoons or a digital kitchen scale
- Rubber spatula or wooden spoon
- Parchment paper
- Wire cooling rack
Ingredients
For The Crust
- ½ cup butter, plus 2 tbsp, room temperature to soft
- ¼ cup sugar
- 1 ¼ cup all-purpose flour
- ¼ teaspoon salt
For The Custard
- ¾ cup sugar
- 1 large egg , plus 2 egg yolks
- ¼ cup all-purpose flour
- ¼ teaspoon salt
- 3 cups rhubarb, fresh or frozen, chopped into 1-inch (3-mm) pieces
Instructions
Make The Shortbread Crust
- Preheat the oven to 350ºF (180ºC) and line an 8 or 9-inch (20 or 23-cm) square baking dish with parchment paper.
- In a mixing bowl, beat the butter and sugar together until light and fluffy, about 1 to 2 minutes.
- Add the flour and salt, and continue to mix on low until the dough is crumbly with no visible flour remaining.
- Dump the dough crumbs into the prepared baking dish. Use your hands to first spread, then press the crust evenly into the pan creating a tightly packed shortbread layer.
- Place the crust into the preheated oven for 24 to 26 minutes or until the edges turn slightly golden. Remove the crust from the oven and place it on a wire cooling rack.
Make The Custard
- While the crust is in the oven, make the custard. Using the same mixing bowl, combine the sugar, egg, and yolks. Mix everything together on low speed until smooth.
- Add the flour and salt to the mixture and continue to mix on low until no visible streaks of flour remain, scraping the sides of the bowl down halfway through mixing.
- Add the chopped rhubarb to the custard and fold it in gently until well coated.
- Pour the rhubarb custard mixture over the pre-baked shortbread crust. Use a rubber spatula or fork to spread the rhubarb into an even layer.
- Place the baking dish back in the oven and bake the rhubarb custard bars for 42 to 45 to minutes, or until the custard is set. Place the baking dish on a wire rack and cool the bars completely before slicing.
Notes
Top Tips
1. Peel the Rhubarb. If your rhubarb is older or the stalks are really thick, peel them for the best taste. 2. Cool Before Slicing. The bars need to be fully cool before cutting into squares because the custard is too soft when it’s still warm. 3. Eat Fresh. Custard bars don’t freeze well as a general rule, so plan to make these when you can eat the whole batch in a day or two.Recipe Notes
- Don’t worry if your custard turns light gold in places while baking—this is normal!
- Frozen rhubarb will work here, however, you may need to bake the bars a bit longer.
- It’s pretty important to let the bars cool before slicing because the custard needs time to set.
How To Store & Freeze Rhubarb Custard Bars
- To Store: Place the sliced bars in an airtight container and store at room temperature for the first day. After that, store the container in the fridge. Baked custard doesn’t store fabulously, and can make the shortbread soggy.
- To Freeze: These bars don’t freeze well so eat them within a couple of days.
Substitutions & Variations
- If you want your bars a bit sweeter, replace half of the rhubarb with sliced strawberries. Please note, strawberries contain more water than rhubarb so the custard may take longer to set in the oven.
- For extra flavour, add lemon zest, orange zest, or a teaspoon of finely chopped fresh ginger to the custard if you like.
- To make this recipe dairy-free, use a good quality vegan butter.
- To make gluten-free rhubarb custard bars, sub a good GF flour blend (like the Bob’s Red Mill one) for the all-purpose flour. There are probably other flours that will work as a shortbread base since it doesn’t need to rise, but we haven’t tested any.
Pat says
These are SO good. Since rhubarb season is over and I like to use fresh ing, is there a fruit you culd suggest to use with this recipe other thatn rhubarb?
Alexandra Daum says
Plums would be really nice, or blackberries!
Jan says
I love these bars but can you use frozen rhubarb.
Kelly Neil says
Hi Jan! Yes frozen rhubarb is fine and is listed in the recipe card! :)