Last updated on June 13th, 2025
Table of contents
This Old Fashioned Rhubarb Crunch is a layered dessert made with tart, fresh-picked rhubarb, nestled between a buttery oat crisp topping. My vintage inspiration for this nostalgic dessert is straight from my grandmother’s handwritten recipe box. This easy rhubarb recipe is delicious when topped with a dollop of vanilla ice cream or homemade whipped cream and served at Spring brunch.🌸
If you are a rhubarb fan, be sure to try my Rhubarb Sourdough Muffins or Strawberry Rhubarb Pie Recipes!
Ingredients
Filling
- Rhubarb is hardy plant with edible stalks, harvested in the Spring, and known for its tart, sour taste.
- Sugar is a made by processing the juice of the sugarcane plant. Cane sugar is a natural option that is less processed with a slightly courser texture.
- 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.
- Vanilla provides hints of caramel and spice, enhancing the depth of flavor to baked goods. The best quality is an all-natural and made from real vanilla beans containing at least 35% alcohol.
Crunch
- All-purpose unbleached flour is made from ground wheat kernels with the bran and germ removed. It has a moderate protein content of 10-12%, making it a versatile option for most baked goods.
- Oats are a whole grain high in fiber and available as whole old-fashioned oats, or quick oats, which are finely cut and partially pre-cooked.
- Brown sugar is granulated sugar combined with molasses, sold as either light brown sugar (with 3.5% molasses) or dark brown sugar (with 6.5% molasses) for a more robust flavor.
- 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.
- Pink salt is a type of rock salt found near the Himalayas, that is minimally processsed and contains trace minerals.
- When making crumb topping, use soft, room temp butter since melted butter makes the crumb soggy.
- Aluminum baking pans that are light in color are best for conducting even heat. Use a 8″ or 9″ baking pan for thicker bars or 9×13″ glass pan for thin bars.
- 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.
- If using frozen rhubarb, do not let it thaw, rather mix it into the boiled sugar mixture and pour on top of the bottom layer.
- This dessert is best when served the same day as the crisp topping may become soggy.
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 to help hydrate the flour.
- Reduce the oven temperature by 25°, as gluten-free flour is delicate and could burn before the center is done.
- Gluten-free baked goods dry out quickly, so put them in a sealed container right away.
TO MAKE VEGAN/DAIRY FREE
- Swap out the butter with unsalted vegan butter sticks such as Violife.
Equipment
Recommended tools: (affiliate links)
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How to pick and preserve fresh-picked rhubarb
- Pick rhubarb very early in the morning before the bugs are active and to avoid the sun.
- To refrigerate: put rhubarb stalks in an air-tight container and store in the fridge for 1 to 2 weeks.
- To freeze: place chopped rhubarb in a single layer on a 1/2 sheet pan lined with parchment paper. Freeze for 1 hour or until firm, and then place in ziploc bags or vacuum seal them for up to 1 year.
Related Recipes
Ingredients
Equipment
Method
- Dice the rhubarb in a separate bowl and set aside. Melt butter and set aside.
- Preheat the oven to 350°
- In a mixing bowl put flour, oats, sugar and cinnamon. Pour melted butter over dry ingredients and mix together.
- Place 2/3 of the mixture into the bottom of the baking dish and press until smooth. (Save the remaining 1/3 for the top)
- Spread chopped rhubarb all over the bottom layer.
- In a saucepan mix together the sugar, ClearJel, water, vanilla and cook until a thick and clear sauce. Pour over the rhubarb.
- Sprinkle the remaining 1/3 crumb mixture on top.
- Top with the remainder 1/2 of the crumb mixture and bake at 350° for 1 hour.
- Serve warm with a scoop of ice cream or whip cream.
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