Preheat the oven to 325℉. Lightly oil the sides of a 8" cake pan with coconut oil. Place a circle of parchment paper on the bottom of the pan to make removing the cake easy.
In a large mixing bowl, whisk together the flour, oat flour, baking powder, salt, and sugar.
Add the melted butter, oil, egg, yogurt, and vanilla. Stir until a smooth batter forms. The batter should be thicker than traditional cake batter.
Pour the batter into the cake pan and make sure it is spread evenly in the pan.
Bake the cake for 30-35 minutes. A toothpick inserted into the center of the cake should come out clean and when you press the cake gently it should bounce back.
Allow the cake to cool in the pan for 10 minutes. Then removed the cake from the pan (make sure you peel off the parchment paper on the bottom) and allow the cake to cool completely before topping with cream and berries.