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This gluten free rhubarb crumb cake perfectly captures the tart brightness of rhubarb with a soft vanilla cake base and a crunchy streusel topping. It’s a dessert that combines fresh seasonal flavors and a variety of textures, making it a delightful treat for gatherings or a special afternoon snack. The cake balances the sharpness of rhubarb with smooth yoghurt and a buttery crumb that is simply irresistible.
I first baked this cake during rhubarb season to use up an abundance of stalks and it quickly became a family favorite. Every time I make it, I am reminded how something so simple can feel so special.
Ingredients
- Rhubarb stalks: cut into roughly half inch pieces for tender texture and vibrant color
- Caster or superfine sugar: to dissolve quickly and sweeten without graininess
- Freshly squeezed lemon juice: to enhance rhubarb’s natural tartness and keep flavors bright
- Vanilla bean paste or extract: for a fragrant note within the rhubarb filling
- Cornstarch: mixed with water to thicken the rhubarb juices and create a jam-like consistency
- Softened unsalted butter: for richness in the streusel topping and cake
- Gluten free plain flour blend: that suits baking without xanthan gum when blended with almond flour
- Almond flour: adds moistness and a subtle nuttiness to the crumb and cake layers alike
- Xanthan gum: for structure since the flour blend is xanthan gum free
- Full fat plain or Greek yoghurt: for moisture and a slight tang sealing the crumb cake’s tender crumb
- Baking powder and baking soda: to give the vanilla cake just the right lift and crumb structure
- Room temperature eggs: to help maintain emulsion and ensure the cake is light and fluffy
Step-by-Step Instructions
- Sauté the Rhubarb Filling:
- Combine rhubarb pieces sugar lemon juice and vanilla in a saucepan over medium heat. Stir occasionally and cook until rhubarb is tender and releases its juices about 3 to 4 minutes. Remove from heat.
- Make and Add Cornstarch Slurry:
- In a small bowl mix cornstarch with water to form a smooth slurry. Stir this into the warm rhubarb mixture and return to heat. Stir continuously over low heat for about 1 minute until thickened to a jam-like texture. Pour into a bowl and allow it to cool completely.
- Prepare the Streusel Topping:
- Mix softened butter sugar and vanilla in a bowl using a wooden spoon until combined but do not overcream. In a separate bowl whisk the gluten free flour almond flour xanthan gum and salt. Add dry ingredients to butter mixture and mix until it forms a clumpy dough. Knead lightly until homogeneous and set aside.
- Make the Vanilla Cake Batter:
- Cream sugar butter oil and vanilla in a large bowl until pale and fluffy by hand or mixer. Add eggs one at a time mixing well after each to keep the emulsion stable.
- Make the Vanilla Cake Batter (continued):
- Whisk together gluten free flour almond flour baking powder baking soda xanthan gum and salt in another bowl. Add half of the dry mix to wet ingredients and mix until combined. Stir in yoghurt until smooth then add remaining dry ingredients. Whisk thoroughly until no lumps remain.
- Assemble and Bake:
- Pour the vanilla cake batter into the lined baking pan and smooth the top evenly. Spoon the cooled rhubarb filling over the batter spreading it to cover evenly but leaving a few spots of batter showing. Crumble streusel evenly over the rhubarb layer making sure it is spread out well. Bake in a preheated oven at 350 degrees Fahrenheit or 180 degrees Celsius for 40 to 45 minutes until streusel is golden and a toothpick inserted comes out clean.
- Cooling and Serving:
- Allow the cake to cool in the pan until warm but not hot to prevent crumbling when removing. Serve warm or at room temperature optionally dusted with powdered sugar before slicing.
My favorite part of this cake is the tart rhubarb filling which really wakes up the taste buds without being overly sweet. One spring, my family gathered to harvest fresh rhubarb and bake this cake together which made it even more special and memorable.
Storage Tips
Store this cake uncovered or loosely covered at room temperature to keep the streusel topping crisp. Avoid airtight containers as moisture softens the crunchy crumb. It stays fresh for about three to four days making it ideal for weekend entertaining or gifting. Leftovers make a lovely companion to morning coffee.
Ingredient Substitutions
If you cannot find rhubarb use tart green apples finely chopped and cooked down with lemon juice for a similar tart filling. Almond flour can be swapped with ground hazelnuts for a different nutty layer. If xanthan gum is in your flour blend already omit it here to avoid gummy textures. Butter can be replaced with coconut oil for a dairy-free option.
Serving Suggestions
This crumb cake is wonderful served with a dollop of whipped cream or a scoop of vanilla ice cream. A drizzle of honey or maple syrup adds extra sweetness if desired. It pairs beautifully with a cup of black tea or freshly brewed coffee to balance the tartness and buttery flavors.
Cultural Context
Rhubarb is a traditional ingredient in Northern European baking favored for its tart flavor and early spring availability. Crumb toppings originated in German and American kitchens where buttery crunchy textures are beloved additions to cakes and pies. This cake reflects a fusion of classic flavors adapted for gluten free diets.
Frequently Asked Questions
- How do I ensure the rhubarb filling is not too watery?
Cook the rhubarb gently until softened and its juices released, then thicken with a cornstarch slurry before cooling to allow it to set well within the cake.
- What can I use instead of xanthan gum in the gluten free flour blend?
If your gluten free flour mix already contains xanthan gum, simply omit the additional amount. Otherwise, you can replace it with guar gum or omit it if recipe structure allows.
- Why is it recommended to add eggs one at a time at room temperature?
Adding eggs slowly at room temperature helps maintain a smooth emulsion with the butter, resulting in a tender, well-risen cake texture.
- Can I store this cake and how long will it keep?
Store the cake in a loosely covered container at room temperature for 3-4 days to keep the crumb topping crisp and the interior moist.
- How do I prevent the crumb topping from becoming too soft?
Avoid sealing the cake in airtight containers; a loose cover allows the topping to stay dry and maintain its crisp texture.
- Is it necessary to cool the rhubarb filling before assembling?
Yes, cooling the filling to room temperature prevents the batter from becoming too loose and helps maintain distinct layers.
