Preheat your oven to 350 degrees. Grease a nine inch baking pan with butter or coconut oil. Set aside.

In the bowl of your stand mixer beat the unsalted butter and sugar until fluffy. Add the eggs and vanilla, beat until mixed in. Add the gluten free flour, baking powder and salt. Mix just until the ingredients are combined to form a cake batter.

Pour the cake batter into the greased nine inch baking dish. 

Cover the top of the cake batter with the sliced plums.

In the bowl of your stand mixer combine the rolled oats, brown sugar, brown rice flour, sea salt, melted butter and walnuts. Blend until a crumble forms.

Pour the crumble evenly over the sliced plum layer of the cake. 

Bake at 350 degrees for 55 minutes or until the top is golden brown and the plum layer is bubbling.

Once the cake is cool store it in the refrigerator.

If you made this recipe please leave a star rating and comment below. It helps other readers find this recipe and means so much to me.