Preheat oven to 350°F.

Grease an 8×8 inch square baking pan using butter or coconut oil. Set aside.

In a small saucepan, combine the prunes, red wine, coconut sugar, and balsamic vinegar. Stir to combine. Bring to a boil over high heat. Once it has come to a boil, reduce heat to low and allow the sauce to simmer, stirring occasionally, until the liquid has reduced by a little but more than half, to a thick consistency, and the prunes have largely broken down, about 30 minutes.

In a medium bowl, add the flour, baking powder, baking soda,  cinnamon, and salt. Stir to combine. Set aside.

Using a stand mixer or a bowl with a hand mixer, combine the butter, white sugar, and brown sugar, mixing until fully creamed together. Adding one egg at a time, blend each until fully incorporated. Remember to scrape down the sides of the bowl to combine all ingredients. Add the dry to the wet ingredients and continue to mix until fully combined.

Spoon the batter into the greased pan and spread out evenly. Spoon the prune sauce evenly over the batter. Then, using the back of the spoon with a swirling motion, mix the prune sauce with the top layer of batter to create a marbleized effect.

Bake for 25 to 30 minutes if using paleo or gluten-free flour and about 40 minutes for regular cake flour, until golden brown and/or when a toothpick comes out clean. Cool for 15 minutes before slicing into squares. Enjoy!