Rhubarb Muffins with Sourdough Discard and Oat Crumble

Bake a little comfort into your day with these sourdough discard rhubarb muffins. Bursting with tart diced rhubarb and finished with a buttery oat crumble, they’re tender on the inside with a lightly crisp topping — ideal for breakfast, brunch, or a cozy coffee break.

When I had extra sourdough starter on hand and a bunch of fresh rhubarb begging to be used, I adapted a simple sourdough muffin batter into these rhubarb muffins and added a sweet oat crumble. The result was a batch of plump muffins with tall, domed tops and a tender crumb. They were a hit with overnight guests and disappeared faster than I expected — but not before I managed to get a few photos.

Why You’ll Love this Recipe

A smart way to use sourdough discard. If you maintain a starter, you’ll often have discard to use up — this recipe turns that into a flavorful baked good rather than wasting it.

Flexible with fruit. If you don’t have rhubarb, swap in strawberries, blueberries, or other fruit. The batter adapts well to fresh or frozen fruit.

Make-ahead friendly. The batter can rest in the fridge overnight and be baked in the morning for fresh muffins. If you’re short on time, you can also bake them right after mixing.

Ingredients you’ll need for these sourdough discard muffins

(Printable recipe card information is included in the recipe section below.)

• 2 cups all-purpose flour
• 1 1/2 teaspoons baking powder
• 1 teaspoon baking soda
• 1/2 teaspoon salt
• 1/2 cup melted butter
• 1 tablespoon olive oil
• 1 cup packed brown sugar
• 2 large eggs
• 1/2 cup sourdough discard
• 1/4 cup milk
• 1/2 cup thick Greek yogurt (plain recommended; vanilla-cinnamon worked well here)
• 1 teaspoon ground cinnamon
• 1 teaspoon vanilla extract
• 1 1/2 cups diced rhubarb

For the sweet oat crumble topping:

• 3 tablespoons melted butter
• 1/4 cup all-purpose flour
• 1/4 cup old-fashioned rolled oats
• 1/3 cup packed brown sugar

Instructions

1. Preheat and prepare: When you’re ready to bake, preheat the oven to 425°F (220°C). Grease a muffin tin or line it with paper cups.
2. Dry ingredients: In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and cinnamon.
3. Wet ingredients: In a large bowl, whisk the melted butter, olive oil, eggs, brown sugar, sourdough discard, milk, Greek yogurt, and vanilla until smooth.
4. Combine: Fold the dry ingredients into the wet ingredients until just combined — avoid overmixing.
5. Add rhubarb: Gently fold in the diced rhubarb with a rubber spatula until evenly distributed and no loose streaks of flour remain.
6. Chill if desired: You can bake immediately or cover the batter and refrigerate overnight for a slightly tangier, more developed flavor.
7. Make the crumble: In a small bowl, combine the melted butter, flour, oats, and brown sugar with a fork until crumbly. Chill briefly if possible so it holds together when placed on top of the muffins.
8. Fill tins: Use an ice cream scoop or large spoon to fill each muffin cup nearly full. For taller, bakery-style domes, keep an empty space between muffins (use two tins and leave every other cup empty).
9. Top and bake: Sprinkle and gently press the oat crumble over each muffin. Bake at 425°F for 5 minutes, then reduce the oven temperature to 350°F (175°C) and bake an additional 18–20 minutes, or until the tops spring back when touched or a toothpick comes out clean.
10. Cool: Let muffins cool in the pan a few minutes, then transfer to a wire rack to finish cooling.

Grandma Rita’s Kitchen Tip

To get tall, bakery-style muffin tops, leave space between filled cups in the muffin tin (every other cup empty). Bake five minutes at 425°F to jump-start the rise, then reduce to 350°F and finish baking for 18–20 minutes. Muffins are done when they spring back lightly or a tester comes out clean.

Substitutions and variations

• Swap the rhubarb for blueberries or diced strawberries — fresh or frozen both work.
• Use 3/4 cup buttermilk in place of the 1/4 cup milk plus 1/2 cup Greek yogurt for a tangy, single-liquid option.
• For a sweeter, less-oaty topping, replace the 1/4 cup rolled oats with an extra 1/4 cup flour.
• Increase the rhubarb if you prefer fruitier muffins — just fold it in gently to avoid overworking the batter.

How to store these rhubarb muffins

These muffins taste best fresh. Once completely cool, store them in an airtight container at room temperature for up to 3 days. To keep the crumble topping crisp, place a paper towel over the muffins before sealing the container.

To refresh after a day, warm a muffin in the microwave for 8–12 seconds. To freeze, place cooled muffins in an airtight container or freezer bag and freeze up to 3 months; thaw at room temperature or warm briefly before serving.

Other rhubarb and sourdough ideas

• Try a baked rhubarb pudding or crisp when you have extra stalks.
• Use sourdough discard in other baked treats: crackers, quick breads, or discard brownies are all good options.

Recipe summary

Yield: 12 muffins. Prep time: about 15 minutes (plus optional overnight chill). Cook time: ~25 minutes. Total time: ~40 minutes. These sourdough discard rhubarb muffins are a reliable way to use starter discard and seasonal rhubarb for a flavorful breakfast or snack.