Crisps are one of my favourite easy ways to use up fresh or frozen fruit, and this gluten-free rhubarb crisp is a knockout winner! It literally has every texture and flavour you could possibly want in a dessert — soft baked rhubarb, crunchy oat topping, tartness, sweetness, and a hint of spice and salt. Literally what more do you need?
Though we are not a gluten-free household, we do have gluten-intolerant family members. I also simply like the flavour of buckwheat flour so I always have it on hand and bake with it often.
This recipe calls for a total of 1 cup of sugar, which is kind of a lot for one square baking dish. If sugar is a concern, you can reduce the amount, however, keep in mind you do need some sweetness to balance the tart rhubarb. If you reduce the amount of sugar be prepared for your lips to pucker! Keep scrolling to the notes section below for more information and tips, as well as FAQs and substitutions.
Preheat the oven to 350ºF (180ºC) and lightly grease an 8-inch (20-cm) square or round baking dish with butter.
In a large bowl, stir together the chopped rhubarb and lemon juice.
Mix together the sugar and cornstarch in a smaller bowl. Sprinkle the mixture over the rhubarb. Stir well to combine then set aside.
In a second larger bowl, combine the buckwheat flour, brown sugar, oats, cinnamon, and salt.
Mix everything together with your hands, breaking up any large chunks of brown sugar by rubbing them together with your fingers and thumbs.
Add the butter to the oat mixture.
Again with your hands, rub the butter into the buckwheat and oats using your fingers and thumbs. When all of the butter has been incorporated, with no bits of dry flour remaining in the bottom of the bowl, it’s ready.
Give the rhubarb a good stir then pour it into the prepared baking tin. Spread the rhubarb out in an even layer, then top it with the buckwheat-oat mixture.
Place the tin in the oven and bake the gluten-free rhubarb crisp for 40 to 45 minutes, or until the top is golden and the rhubarb is bubbling for a minimum of five minutes. Cool the crisp on wire rack for 15 minutes before serving warm, with ice cream or whipped cream.
Notes & Tips
If using fresh rhubarb for gluten-free rhubarb crisp, be sure to wash it first to rinse away dirt or tiny critters hanging on from the garden.
To use frozen rhubarb, there’s no need to thaw first. Simply proceed with the recipe as written.
If your stalks of rhubarb are huge, slice them in half lengthwise before chopping into chunks.
To keep this recipe gluten-free use certified gluten-free buckwheat flour and oats.
This gluten-free rhubarb crisp is evenly balanced with rhubarb filling and oat topping. If you like more fruit in your crisp, add up to 2 cups (300 g) more of chopped rhubarb. The baking time may change so watch for a golden top and bubbling fruit in the oven.
I mix the sugar and cornstarch in a small bowl before adding them to the rhubarb. This method ensures an even, lump-free coating, however, add them straight to the rhubarb without pre-mixing if you want.
Let the fruit in the gluten-free rhubarb crisp bubble in the oven for a minimum of five minutes to help ensure a properly thickened filling.
Quick oats can be substituted for rolled oats in gluten-free rhubarb crisp but won’t have the same texture.
I have substituted brown rice flour for buckwheat flour with great results.
If gluten-free isn’t a requirement you can substitute all-purpose flour or light spelt flour.
Make gluten-free rhubarb crisp dairy-free by substituting a good quality dairy-free margarine or solid coconut oil.
If you don’t have fresh lemon juice use bottled.
I chose cornstarch as the thickener for gluten-free rhubarb crisp, however, arrowroot powder or tapioca starch are also good options.
Why is my rhubarb crisp runny?
How do you cut rhubarb for crisp?
Do you peel rhubarb before cooking?
Do you thaw frozen rhubarb before baking?
Should you cover crisp while baking?
More Rhubarb Recipes
Rhubarb Curd Creamy, tart, and sweet, use it on toast, ice cream, stir it into yogurt, spread it between cake layers, and so much more.
Maple Rhubarb Jam With Cardamom Lightly sweetened with maple syrup, this is a gorgeous small batch ruby red jam.
Rhubarb Fool With Cardamom Cream Layers of poached rhubarb and cream make for a show stopping dessert!
Rhubarb Scones With Fresh Ginger Rhubarb scones are a favourite spring treat! Spicy fresh ginger is a great match for the rich cream scone base and tart chopped rhubarb.
Printable Recipe Card
Gluten-Free Rhubarb Crisp
- 1 8-inch (20-cm) square or round baking dish glass or metal
- measuring cups and spoons or digital kitchen scale
- 2 large mixing bowls
- rubber spatula or wooden spoon
- wire cooling rack
For The Rhubarb Filling
- 4 cups rhubarb, washed, chopped into ½ inch (1 ¼ cm) chunks
- 2 teaspoons lemon juice
- ½ cup sugar
- ¼ cup cornstarch
For The Buckwheat Oat Topping
- ½ cup buckwheat flour
- ½ cup brown sugar, tightly packed
- ½ cup rolled oats , also called large flake oats
- 1 teaspoon cinnamon, ground
- ⅛ teaspoon salt
- ½ cup butter, room temperature
- Preheat the oven to 350ºF (180ºC). Lightly grease an 8-inch (20-cm) square or round baking dish with butter.
- In a large bowl, stir together the chopped rhubarb and lemon juice.
- Mix together the sugar and cornstarch in a smaller bowl. Sprinkle the mixture over the rhubarb. Stir well to combine then set aside.
- In a second larger bowl, combine the buckwheat flour, brown sugar, oats, cinnamon, and salt. Mix everything together with your hands, breaking up large chunks of brown sugar by rubbing them together with your fingers.
- Add the butter to the oat mixture. Again with your hands, rub the butter into the oats. The topping is ready when all of the butter has been incorporated, and no dry bits of buckwheat flour remain in the bottom of the bowl.
- Give the rhubarb a good stir then pour it into the prepared baking tin. Spread the rhubarb out into an even layer, then top it all over with the buckwheat mixture. Place the crisp in the oven and bake it for 40 to 45 minutes, or until the top is golden and the rhubarb is bubbling for at least five minutes. Cool the crisp on wire rack for 15 minutes before serving warm with ice cream or whipped cream.