Tangy Rhubarb Sourdough Discard Muffins with Oat Crumble

Bake up a batch of warm, tender sourdough discard rhubarb muffins—dotted with tangy rhubarb and finished with a sweet oat crumble. These muffins are moist inside with a crunchy topping, making them ideal for breakfast, brunch, or an afternoon coffee break.

When I had extra sourdough starter and a bunch of fresh rhubarb, I adapted a basic sourdough muffin batter into these discard muffins with a sweet oat crumble. They developed tall, domed tops and a tender crumb—so good that I nearly ran out before I managed to photograph them. This recipe is forgiving, flexible, and a delicious way to use up discard.

Why you’ll love this recipe

• Waste not, want not: This recipe makes excellent use of sourdough discard, adding a gentle tang and tender texture.
• Fruit-friendly base: The batter works well with other fruits—swap rhubarb for strawberries, blueberries, or diced peaches if you prefer.
• Make ahead: The batter can be mixed and refrigerated overnight, then baked fresh in the morning for an effortless start to the day.

Ingredients

Yields: 12 muffins

• 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 brown sugar
• 2 eggs
• 1/2 cup sourdough discard
• 1/4 cup milk
• 1/2 cup thick Greek yogurt (plain recommended; vanilla cinnamon works if that’s what you have)
• 1 teaspoon 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 oven to 425°F (220°C). Prepare muffin tins by spraying with nonstick spray or lining with paper muffin cups.
2. In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and cinnamon.
3. In a large bowl, whisk the melted butter, olive oil, eggs, brown sugar, sourdough discard, milk, Greek yogurt, and vanilla until smooth and combined.
4. Add the dry ingredients to the wet ingredients and stir gently until just combined. Do not overmix; a few small lumps are fine.
5. Fold the diced rhubarb into the batter until evenly distributed and there are no visible streaks of flour.
6. To make the oat crumble topping, mix the melted butter, flour, rolled oats, and brown sugar in a small bowl with a fork. Chill the topping briefly so it firms slightly before using.
7. Use an ice cream scoop or large spoon to fill each muffin cup nearly to the top—the batter is thick. For taller, bakery-style tops, leave an empty space between cups by using two tins and filling every other cup.
8. Sprinkle or press a generous spoonful of the oat crumble onto each muffin.
9. Bake at 425°F for 5 minutes, then reduce the oven temperature to 350°F (175°C) and continue baking for 18–20 minutes, or until the tops spring back when gently pressed or a toothpick inserted into the center comes out clean.
10. Allow muffins to cool in the pan for a few minutes before transferring to a wire rack to cool completely.

Grandma Rita’s Kitchen Tip

For bakery-style domes, leave an empty space between muffin wells (fill every other cup). Start at 425°F for five minutes to encourage rise, then reduce the oven to 350°F and finish baking. 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) for a different flavor.
• Substitute 3/4 cup buttermilk for the 1/4 cup milk plus 1/2 cup Greek yogurt for a tangy, single-liquid option.
• To make a sweeter, less textured topping, use 1/4 cup flour instead of rolled oats.
• If you prefer more fruit, increase the rhubarb amount—just fold gently so the batter doesn’t get overworked.

How to store the muffins

These muffins are best the day they’re baked, but they keep well for several days. Once completely cool, store in an airtight container at room temperature for up to 3 days. To help preserve the crumble’s texture, place a paper towel over the muffins before sealing the container.

To refresh slightly stale muffins, warm in the microwave for a few seconds (about 10 seconds, depending on your microwave). To freeze, place cooled muffins in an airtight container or freezer bag and freeze for up to 3 months; thaw at room temperature or warm briefly before serving.

Nutrition (approximate per muffin)

Calories: 315 • Total Fat: 13g • Saturated Fat: 7g • Cholesterol: 60mg • Sodium: 373mg • Carbohydrates: 44g • Fiber: 2g • Sugar: 21g • Protein: 6g

Other rhubarb ideas

• Baked sticky rhubarb pudding (a pudding-cake with a crunchy top)
• Classic rhubarb crisp with an oat topping
• Old-fashioned rhubarb coffee cake

Other sourdough discard uses

• Sourdough discard chips or crackers
• Honey oat sourdough sandwich bread
• Sourdough discard brownies for a fudgy treat
• Dutch oven sourdough bread (step-by-step method)

Did you make this recipe?

If you try these sourdough rhubarb muffins, leave a note about how they turned out or share a photo—I’d love to hear your results and any tweaks you make.