Blueberry & Rhubarb Crumb Coffee Cake with Coconut Sugar & Sourdough
It’s still peak rhubarb time so I wanted to make another sweet treat using this delicious vegetable (it’s actually not a fruit!). I took inspiration from one of my favorite cooks/food blogs - Deb Perelman at the Smitten Kitchen. This recipe is an adaptation of her big crumb coffee cake recipe. I made a few notable changes, including, of course swapping out the white sugar and brown sugar for coconut sugar and adding in a bit of sourdough discard. I also had some blueberries on hand and decided to add those in as well. The end result is really just so delicious and you won’t have any of that sugar hangover feeling from eating those traditionally overly sweet coffee cakes that most people are familiar with. I hope you’ll give it a try!
Ingredients
For the blueberry & rhubarb filling:
100 g blueberries
140 g rhubarb, diced
35 g (1/4 cup) coconut sugar
1 tsp. flour
1/2 tsp. ground ginger
For the crumb:
75 g (1/2 cup) coconut sugar
1 tsp. cinnamon
1/2 tsp. ground ginger
1/8 tsp. salt
1/2 cup butter, melted
210 g (1 and 3/4 cup) all-purpose flour
For the cake:
80 g (1/3 cup) sour cream
1 large egg and 1 large egg yolk
2 tsp. vanilla extract
120 g (1 cup) all-purpose flour
75 g (1/2 cup) coconut sugar
1/2 tsp. baking soda
1/2 tsp. baking powder
1/4 tsp. salt
6 tbsp. softened butter, cut into pieces
60 g sourdough starter discard
Directions
Preheat oven to 325 F and grease a 9x9 square baking pan.
For the filling, combine all of the ingredients together and set aside.
For the crumb, combine the melted butter with the sugar, cinnamon, ginger, and salt. Then add the flour in and stir until a solid dough firms.
For the cake, in a small bowl, stir together the sour cream, egg, egg yolk, and vanilla extract. In a mixer fitted with the paddle attachment, combine the flour, coconut sugar, baking soda, baking powder, and salt. Then add the butter and a spoonful of the sour cream mixture and mix on medium speed until combined. Then add the remaining sour cream mixture in two batches. Once mixed in, add the sourdough starter and mix until combined.
Scoop out about 1/2 cup of this batter and set aside. Pour the rest of the batter into the baking pan. Top with the blueberry & rhubarb mixture. Then dollop the batter you set aside on top (does not have to be even). Lastly, crumble the crumb mixture over the top, leaving the crumbs as big or as small as you would like.
Bake for 45-55 minutes, or until a toothpick inserted in the center comes out clean (it might be a bit moist from the blueberries/rhubarb but should not have any cake batter on it).
