Sourdough Blondies with Rhubarb & Almonds

Fresh rhubarb elevates these easy sourdough blondies from overly sweet to enticing, a little tart, and irresistible. Paired with sliced almonds, these sourdough discard blondies are a perfect early summer treat when rhubarb is in season.

Typically, blondies can be a hard sell for me. I definitely gravitate toward brownies if I’m looking for a dessert bar. And since I fall firmly into the fudgy brownie fan club and blondies are typically more cakey, I often overlook them. Sorry, blondies!

However, I was determined to make a delicious, somewhat fudgy, not overly sweet sourdough blondie with this recipe. And honestly, it wasn’t easy! It went through five iterations to get the texture exactly right. At first, they were too cakey (although very good, and I list how to make them more like a rhubarb cake below if you’d prefer) and then they were too soggy from excess rhubarb juices.

After multiple recipe attempts though, I can now say these are excellent blondies that hit all of the notes that I want from a great blondie. They’re a little fudgy, a little tart from the rhubarb, and have an excellent butterscotch flavor.

Are they better than brownies to me? No, but they stand on their own and are certainly the best blondies I’ve ever had!

👉 Be sure to check out some of my other favorite sourdough discard recipes and learn everything you need to know about sourdough discard in this all-encompassing sourdough discard guide.

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What are Blondies and What Make These so Good?

Sometimes blondies are called brownies without chocolate, but that’s a little unfair to these dessert bars!

Blondies rely on vanilla, brown sugar, and butter for a sweet butterscotch flavor. They’re often dappled with chocolate chips or white chocolate chips and have a denser texture than brownies.

Usually, blondies have a cake or cookie-like consistency and are cloyingly sweet. Whereas brownies have bitter chocolate to offset some of their sweetness, blondies tend to lean into the buttery sugary-ness of it all.

However, these sourdough blondies offer so many characteristics that make them unique!

First of all, fresh rhubarb is a little tart and adds a much-needed acidity to the blondies, along with the slight tang of sourdough discard. Like other rich desserts such, fruit (well, rhubarb is technically a vegetable) is a great tool to offset the sweetness and leave our mouths watering for more. Think key-lime pie or lemon bars!

Then, the pairing of rhubarb and almonds goes so well together. I add sliced almonds and a little almond extract to the batter to give it a little amaretto flavor.

Finally, the texture is much more fudgy. This happens with these blondies for a few reasons: there’s only one egg in the recipe, there’s no baking powder, and the rhubarb adds some extra moisture to the batter. With a crunchy topping of raw sugar and almonds, you get a more interesting textural experience eating these blondies.

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🛠 Tools Needed for Sourdough Blondies:

Click the links below for my tool recommendations.

• Baking Scale
• 8×8-inch Baking Pan
  • This recipe was developed using a basic 8×8-inch square baking pan. If you only have a 9-inch pan, the blondies will bake faster and be thinner. Take them out of the oven sooner if you’re using a larger pan.
• Spatula

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🛒 Ingredients Needed for Sourdough Blondies:

Click on the links below for my ingredient recommendations.

• All-Purpose Flour
• Kosher Salt
• Granulated Sugar
  • The granulated sugar is only used to macerate the rhubarb and remove some of its juices. Like salt, sugar is hydrophilic and will draw out some of the excess liquid from the rhubarb so you don’t end up with soggy blondies.
• Dark Brown Sugar
  • The dark brown sugar lends a more pronounced butterscotch flavor to the blondies, but you’re welcome to use light brown sugar in its place or a mix of both!
• Sliced Almonds
  • You could also use slivered almonds or chopped whole almonds. I think thinly sliced almonds look the best, though!
  • If you don’t like almonds or are allergic, you can skip them (along with the extract) in this recipe.
• Almond Extract
  • If a recipe has almonds in it, I love using almond extract to put the almond flavor over the edge, like in my Easy Sourdough Discard Granola Recipe. It’s subtle, but such a lovely addition to these blondies and pairs well with the rhubarb.
• One Egg
  • I recipe-tested these blondies with two eggs, which came out a little too cakey for my preference. If you prefer a cakey blondie though, you may want to add another egg.
• Sourdough Discard
  • You can use an active sourdough starter in this recipe; however, it is unnecessary since the batter isn’t leavened.
  • If you don’t have a sourdough starter, learn how to make one in a week with my day-by-day guide.
• Vanilla Extract
• Unsalted Butter, melted and cooled
• Raw sugar, for topping
  • The raw sugar (demerara or turbinado) will make the top crust shiny and a little more crunchy. It’s a nice trick for baked goods like these blondies or my Sourdough Discard Blueberry Scones.

A note on Rhubarb:

• For best results, use fresh rhubarb. However, you can use frozen rhubarb as well. Just let the rhubarb thaw for an hour before macerating. When I tested with frozen rhubarb, I noticed that the blondies were slightly wetter, so be sure to get as much liquid out as you can when you macerate it.
• During late spring and early summer, rhubarb is in season. You can easily find it at well-stocked grocery stores or local farmer’s markets. For this recipe, it’s ideal to opt for thinner rhubarb stalks or simply slice thicker ones in half.

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👨‍🍳 How to Make Sourdough Blondies with Rhubarb & Almonds:

Follow this visual and detailed recipe guide as you bake these sourdough blondies.

1. Macerate the Rhubarb

It’s important to macerate the rhubarb in this recipe or the blondies will be soggy. Because sugar is hydrophilic, it will draw out the juices from the rhubarb.

Chop 136g of fresh rhubarb (about one cup, or two small stalks) into ½-inch pieces and place into a small mixing bowl.

Add 50g of granulated sugar (¼ cup) and toss to coat the rhubarb in the sugar.

Rest for 30 minutes to one hour or until juices leak from the rhubarb. Strain the rhubarb and reserve the juices for another use, such as mixing into cocktails/mocktails or to make rhubarb simple syrup.

2. Whisk Wet Ingredients

Preheat the oven to 350ºF (177ºC).

Oil or butter an 8×8-inch square baking pan and line it with a piece of parchment paper that covers the bottom and has two wings on the sides, allowing easier removal from the pan.

In a medium-sized mixing bowl, whisk together the wet ingredients for the recipe, including:

• 141 grams of unsalted butter, melted (10 TBS)
• 1 large egg
• 200 grams of dark brown sugar (1 cup)
• 1 ½ tsp of vanilla extract
• ½ tsp of almond extract
• 100 grams of sourdough discard

The mixture should be thick and gooey. Be sure to break apart any pieces of brown sugar that have stuck together.

3. Mix Dry Ingredients

Add 100g of all-purpose flour and 1 tsp of salt to the bowl of wet ingredients.

Only stir the batter until there’s no visible flour. Don’t overmix as we’ll be adding in the rhubarb and almonds soon. Overmixing blondie batter will result in a cakier blondie, and we want fudgy for this recipe!

4. Fold in the Rhubarb and Almonds

Stir in about half of the strained rhubarb and about 20g of sliced almonds to the sourdough blondie batter.

Then, pour the rhubarb blondie batter into the prepared baking pan. Use your spatula to spread the thick batter to the edges of the pan. Tap the pan a few times to evenly distribute the batter and remove any air pockets.

Next, sprinkle the rest of the reserved rhubarb and about 10g of sliced almonds on top of the blondies. This is largely for visual effect, but I like showcasing the rhubarb and almonds this way on top of the blondies. That way, there’s no secret about what’s inside!

Finally, sprinkle a couple of tablespoons of raw sugar on top of the blondies. I use turbinado sugar, but demerara or another sprinkling sugar would also look nice so the top of blondies crisp up as they bake. The sugar also adds a nice shine to the tops of the blondies.

5. Bake

Bake the sourdough blondies at 350ºF (177ºC) for 35-40 minutes.

The blondies are done when the edges brown and pull away from the sides and a toothpick inserted into the middle comes out clean.

Cool the blondies completely on a wire rack, before slicing and serving. Use the wings of parchment paper to easily remove the blondies from the pan onto a cutting board.

You can slice and serve the rhubarb blondies many ways, but slicing them into 16 servings (4 horizonal rows by 4 vertical columns) is my favorite way to serve them. That way, they’re smaller blondie servings.

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How to Store Sourdough Blondies:

These blondies keep well at room temperature for four to five days. Keep them covered in an airtight container.

I do not recommend freezing these blondies as they will become a little too soggy after thawing.

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Sourdough Blondies FAQs:

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