Sourdough Blondies with Rhubarb & Almonds

Fresh rhubarb and crunchy almonds elevate these easy Sourdough Blondies, using sourdough discard from overly sweet to enticing, a little tart, and irresistible.

Paired with sliced almonds, these sourdough discard blondies are a perfect early summer and spring treat when rhubarb is in season.

After multiple recipe attempts, I can say these are moist 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.

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🛠 Tools Needed

Click the links below for my tool recommendations.

• Baking Scale, will make for a more consistent bake
• 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

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 farmers’ markets and make Strawberry Rhubarb Jam. 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 just like the sugar in these Sourdough Strawberry Shortcakes.

Chop the fresh rhubarb into ½-inch pieces and place into a small mixing bowl.

Add sugar and toss to coat the rhubarb.

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, then line it with a piece of parchment paper that covers the bottom and has two wings on the sides, making it easier to remove from the pan.

In a medium-sized mixing bowl, whisk together the wet ingredients.

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 the all-purpose flour and 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 raw sugar on top of the blondies for crunch and shine.

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 parchment paper wings to easily transfer the blondies from the pan to a cutting board.

You can slice and serve the rhubarb blondies many ways, but slicing them into 16 servings 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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❓ FAQs