- 1/2 cup butter
- 1 cup white sugar
- 3 stalks rhubarb, cut into 1-inch pieces
- 2 cups gluten-free flour blend
- 2 teaspoons baking soda
- 1/2 teaspoon salt
- 1 cup yogurt
- 1/2 cup coconut oil, melted
- 1 egg
- 1 teaspoon vanilla extract
- Preheat oven to 350 degrees F (175 degrees C).
- Melt butter in a large cast iron skillet or Dutch oven over medium-low heat. Add sugar and rhubarb; cook until rhubarb is soft, 5 to 8 minutes. Remove from heat.
- Mix gluten-free flour, baking soda, and salt together in a large bowl. Add yogurt, coconut oil, egg, and vanilla extract; stir thoroughly until batter is combined.
- Drop cake batter over rhubarb mixture in the skillet. Spread it out gently until mostly smooth.
- Bake in the preheated oven until top is golden and a toothpick inserted into the center comes out clean, about 25 minutes.
- Run a knife around the edges, place a plate on top and carefully invert cake onto the plate.