Last updated on June 13th, 2025
Table of contents
These Sourdough Rhubarb Muffins are made with fresh tart rhubarb, sourdough discard, warm spices and topped with a crunchy crisp topping. They’re perfect for a Spring brunch, a twist on the classic rhubarb crunch dessert, or a way to use fresh rhubarb during its short-lived season. The combination of sourdough discard and buttermilk makes these rhubarb muffins bake up tender and moist, alongside their tangy and sweet punch of flavor.
Wet Ingredients
Wet Ingredients
- Butter is made from churned cream that contains 80% butterfat. European butter is churned longer and has a higher fat content (82%-85%), which is why it yields more flavor.
- Canola oil is perfect for baking as it has a neutral and light flavor. You can swap oil for butter and vice versa as oil provides moisture, and butter provides flavor.
- Sugar is derived from sugarcane and provides sweetness to baked goods. The most common type being granulated white sugar. Cane sugar is a natural option that is less processed with a slightly courser texture.
- Brown sugar is granulated sugar with molasses added, providing deep flavor and moisture to baked goods. Light brown sugar contains 3.5% molasses and dark brown sugar has 6.5%, giving it more robust flavor.
- Buttermilk is a cultured dairy product that adds a tangy flavor and creates tenderness in baked goods. When purchasing buttermilk, look for simple, natural ingredients such as “cultured milk”.
- Eggs are important in baking because their protein provides structure, they are a natural leavener trapping air that expands during baking, and they add moisture to baked goods.
- Vanilla provides hints of caramel and spice, which enhances the depth of flavor in baked goods. Homemade vanilla is best, or use a high-quality, all-natural brand that contains at least 35% alcohol.
- Rhubarb is hardy plant, classified as a fruit, that with edible stalks that have a sour taste and are harvested in the Spring.
- Sourdough discard is the unfed portion of sourdough starter that is removed before the starter is fed with fresh flour and water. *NOTE*If you don’t have starter, just substitute with 1/4 c. buttermilk or sour cream.
Dry Ingredients
- All-purpose unbleached flour with 10-12% protein, such as King Arthur or Sir Galahad Artisan Flour (its bulk-purchased name) which has 11.7% protein. Avoid bread flour, as its higher protein content (11-14%), develops more gluten, which results in dense baked goods.
- Instant ClearJel is a modified food starch used as a thickener, stabilizer, and gelling agent. In baked goods it helps retain moisture and produces a light, tender texture.
- Baking powder is a leavening agent that contains both an acid, like cream of tarter, and a base, like baking soda to help baked goods rise. Use a double-acting aluminum-free baking powder to avoid a bitter aftertaste.
- Baking soda (sodium bicarbonate) is a leavening agent that, when combined with an acid (like lemon juice, buttermilk, or vinegar) creates carbon dioxide gas to make baked goods rise.
- Cinnamon comes from dried bark from the tropical Asian cinnamon tree and is available as whole cinnamon sticks or ground. There are two types: Cassia which has a warm, sweet flavor, and Ceylon known as “true cinnamon”, which has an intense spicy bite.
- Nutmeg is a warm spice that comes from the nutmeg tree in the Spice Islands. It is available as whole nutmeg, grated or pre-ground.
- Pink salt adds essential minerals and nutrients to baked goods.
How to Make Rhubarb Muffins
Step #1
Chop Rhubarb
Step #2
Mix Dry Ingredients
Step #3
Make Crunch Topping
Step #4
Bake & Enjoy
Make your own Ingredients
BUTTERMILK: Add 1 T. vinegar or lemon juice into a liquid measuring cup and add cream or whole milk until it reaches the 1 c. measure line and let it sit for a few minutes before use.
VANILLA: Purchase Grade B vanilla beans (also called extract-grade), which have less moisture and a more concentrated flavor. Place 8 oz. of bourbon (or vodka) in glass bottle or jar. Split 5-7 vanilla beans down the middle and add to bottle. Let it sit for 3-6 months in a cool, dark place. As you use it, continue to replace the bourbon and add more beans as it keeps for many years.
- Do not thaw the fruit before adding them to the dough, as they release liquid and can stain the batter the color of the fruit.
- Before adding the fruit into the batter, toss in a small amount of flour or cornstarch and gently fold in by hand.
- Let muffin batter rest in bowl covered with a towel for 10-15 minutes before scooping into muffin liners to absorb the flour.
- To get high domes on muffins, start oven at at 25° higher temperature for 10 minutes, then reduce oven for the remaining bake time.
- Aluminum muffin pans that are light in color are best for conducting even heat. Lightly spray the top of the muffin pan before putting in the muffin liners. This will prevent the muffins from sticking to the pan in case they spill over the liners.
- Use cornstarch as a substitution if ClearJel is hard to find. For every 1 T. of cornstarch, use 1 1/2 T. ClearJel. For every 2 T. flour or tapioca, use 1 T. ClearJel. You can find it online here.
- Storage: Place baked muffins in an air-tight container up to 3 days. To freeze, cover in saran wrap and place in freezer-safe container up to 6 months. Thaw on counter in the container for 1/2 hour before opening up the container.
- To save time, make batter ahead of time and place in a sealed container in the refrigerator and use within 3-5 days.
Dietary Substitutions
For the past 12+ years, I have owned an all-natural specialty bakery converting conventional recipes to gluten free, vegan, wholesome, etc. Read more about it here.
TO MAKE GLUTEN-FREE
Here are some tips for gluten free baking
- Use a premium gluten-free flour blend.
- Be sure to let the batter rest to help eliminate grittiness. Even letting the batter sit 15 minutes will yield a light and tender baked good. You can let batter sit in the fridge overnight, and up to 3 days.
- Add 1-2 tablespoons additional liquid (use the same liquid called for in the recipe) to help hydrate the flour.
- Reduce the oven temperature by at least 25° to bake low and slow, since gluten-free flour is delicate and tend to burn before the center is cooked through.
- Gluten-free baked goods have a shorter shelf-life than conventional baked goods and dry out faster. Store in airtight container on counter 1-2 days. The refrigerator tends to dry them out more, so it is best to freeze up to 6 months.
TO MAKE VEGAN/DAIRY FREE
- Swap out the butter with vegan butter. I use Violife Plant Butter.
- To replace the egg, place 1 tsp. of baking soda into your baked good and pour 1 T. white vinegar on top of the baking soda.
- Replace the dairy with unsweetened oat milk
Equipment
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Ingredients
Equipment
Method
- Preheat the oven to 350°.
- In a separate bowl dice the rhubarb add 2 T. sugar and set aside.
- Melt butter and set aside.
- Make the topping. In a mixing bowl mix together the flour, oats, brown sugar, butter and cinnamon.
- In a large mixing bowl, whisk together dry ingredients.
- Add in wet ingredients and mix together until just combined.
- Toss the rhubarb in a bit of flour and then stir into the batter. This will help it to not sink to the bottom.
- Let batter rest in bowl 15 minutes with towel over it. Scoop batter into the muffin pan.
- Top the crumb mixture with the diced rhubarb.
- Bake at 350° for 25-28 minutes.
- Store on counter in a sealed container up to 3 days. Freeze up to 6 months.
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