Rhubarb Custard Bars are a tasty treat with a sweet, creamy filling and a crumbly crust. The tartness of rhubarb gives these bars a nice zing that makes them special!
Making these bars feels like a warm hug in dessert form. They’re great for sharing, but I often save some just for me! Perfect with a cup of tea! 
Key Ingredients & Substitutions
Rhubarb: This is the star of your dessert! Fresh rhubarb works best for a bright flavor, but frozen rhubarb is a good alternative. Just thaw it first, and make sure to drain excess moisture to avoid a soggy filling.
Butter: Unsalted butter is preferred as it gives you control over the saltiness. If you’re looking for a dairy-free option, melted coconut oil or a dairy-free buttery spread can work just fine in the crust and frosting.
Sugar: I used granulated sugar in both the crust and filling, but you can swap for brown sugar in the crust for a richer flavor. For a healthier option, coconut sugar can also be used, but it will add a slight caramel flavor.
Eggs: Eggs are crucial for binding the filling. If you need a vegan substitute, use flax eggs (1 tablespoon ground flaxseed mixed with 2.5 tablespoons water for each egg), although the texture might differ slightly.
How Do I Make a Perfect Crust?
The crust is the foundation of these bars, so getting it right is essential. It should be crumbly but also hold together well. Here’s how to ensure success:
- Mix the flour, sugar, softened butter, and salt until crumbly—avoid overmixing.
- Press the mixture evenly into the bottom of your baking pan. Use your fingers or the bottom of a measuring cup to get it nice and flat.
- Make sure to bake until it’s just lightly golden. If you bake too long, it can become tough.
What’s the Best Way to Prepare Rhubarb?
Preparing rhubarb properly keeps the filling flavorful. Start by chopping it into small, even pieces. This way, it cooks evenly:
- After chopping, mix it with sugar and let it sit to draw out the juices. This makes the filling juicy and less tart.
- Make sure to fold the rhubarb mixture gently into your batter to avoid mushiness.
How Can I Achieve a Creamy Frosting?
The frosting adds a lovely finish to the bars. Follow these steps to ensure it turns out creamy:
- Start with room temperature butter. It blends much easier!
- Beat the butter well before adding the powdered sugar; this will make it lighter.
- Add milk gradually for the desired consistency. If it’s too thick, just a bit more milk will help!
How to Make Rhubarb Custard Bars
Ingredients You’ll Need:
For the Crust:
- 1 cup all-purpose flour
- 1/2 cup granulated sugar
- 1/2 cup unsalted butter, softened
- 1/4 teaspoon salt
For the Filling:
- 2 cups rhubarb, chopped (fresh or frozen)
- 1/2 cup granulated sugar
- 2 large eggs
- 1/4 cup all-purpose flour
- 1/4 teaspoon baking powder
- 1/4 teaspoon vanilla extract
For the Frosting:
- 1/2 cup unsalted butter, softened
- 2 cups powdered sugar
- 1 tablespoon milk
- 1/2 teaspoon vanilla extract
How Much Time Will You Need?
This delicious rhubarb custard bars recipe takes about 15 minutes to prepare and an additional 40-50 minutes to bake and cool. Overall, plan for about 1 hour and 15 minutes for the complete process including cooling before serving. Perfect for a delightful treat!
Step-by-Step Instructions:
1. Prepare the Oven and Baking Pan:
Preheat your oven to 350°F (175°C) and grab an 8×8 inch baking pan. Grease it lightly to prevent sticking.
2. Make the Crust:
In a mixing bowl, combine 1 cup of all-purpose flour, 1/2 cup of granulated sugar, softened butter, and 1/4 teaspoon of salt. Use a fork or your fingers to mix everything until it looks crumbly. Press this mixture evenly into the bottom of your prepared pan—this will be the crust.
3. Bake the Crust:
Pop the crust into your preheated oven and bake for about 10-12 minutes, or until it’s just lightly golden. The aroma will start to fill your kitchen!
4. Prepare the Filling:
While the crust is baking, let’s make the filling! In a separate bowl, toss the chopped rhubarb with 1/2 cup of sugar. Let it sit for about 10 minutes so the rhubarb can release some of its juices.
5. Mix the Filling:
In another bowl, whisk the two large eggs until they are frothy. Then add 1/4 cup of flour, baking powder, and 1/4 teaspoon of vanilla extract. Mix everything until it’s smooth. Gently fold in the rhubarb mixture, making sure it’s well combined.
6. Bake the Bars:
Pour the rhubarb filling over the crust and spread it out evenly. Bake in the oven for 25-30 minutes, or until the filling is set but still slightly jiggles in the center. It’s okay if it’s not completely firm; that’s normal!
7. Cool the Bars:
Once baked, take the pan out of the oven and let the bars cool completely on a wire rack. This step is super important if you want clean cuts later!
8. Make the Frosting:
While the bars are cooling, prepare the frosting. In a mixing bowl, beat together 1/2 cup of softened butter, 2 cups of powdered sugar, 1 tablespoon of milk, and 1/2 teaspoon of vanilla extract until the mixture is creamy and smooth. It should look fluffy and delicious!
9. Frost the Bars:
Once the custard bars are completely cooled, spread the frosting evenly over the top. Make it look pretty and inviting!
10. Serve and Enjoy:
Cut the bars into squares and serve. Enjoy your delightful rhubarb custard bars—perfect for sharing or keeping all to yourself!
Can I Use Frozen Rhubarb in This Recipe?
Absolutely! Frozen rhubarb works perfectly in this recipe. Just make sure to thaw it first and drain any excess water before mixing it with the sugar. This will help prevent your filling from being too watery.
How Can I Make the Crust Gluten-Free?
You can easily make the crust gluten-free by substituting all-purpose flour with a gluten-free flour blend. Make sure to check that your other ingredients, like baking powder, are also gluten-free to keep the recipe safe for those with gluten sensitivities.
How Should I Store Leftover Bars?
Store any leftover rhubarb custard bars in an airtight container in the fridge for up to 5 days. You can also freeze them by wrapping individual bars in plastic wrap followed by aluminum foil, where they can last for about 2 months. Thaw in the fridge before enjoying!
Can I Use Different Fruits in This Recipe?
Yes! You can substitute rhubarb with other fruits like strawberries or apples if you’re looking for a twist. Just keep in mind that if the fruit is less tart than rhubarb, you might want to adjust the sugar in the filling slightly to balance the sweetness.
