Stir together the dry ingredients - polenta, coconut flour, gluten-free rolled oats and baking powder. If you want to, you can add spices such as nutmeg and cinnamon to make the kitchen smell even better.
Mash some very ripe bananas in another mixing bowl. The more ripe, the sweeter they are, so this is a great way to use up any that you have lying around. Then, add in nut/seed butter (my favorite is peanut or cashew butter), liquid sweetener and nut milk such as almond or soy. Whisk everything together really well using either an electric whisk or a fork if you don’t have one.
Pour the wet and dry ingredients into a single mixing bowl and stir until they’re well combined.
Add a flax egg and mix to combine. (A flax egg is made by tirring together ground flaxseeds and water. See note in ingredients list.) The batter should be quite sticky and firm, but if it’s too dry and doesn’t stick together well, gradually pour in a bit more plant based milk.
Fold in strawberries, blueberries and flaked almonds. You can add more or less, to your taste.
Pour the polenta cake batter into a lightly greased 9x12 baking dish. Press down the batter quite firmly (this is key to getting a fudgy texture) and if you want to, sprinkle some extra almonds/berries on top.
Bake for 35 minutes. Note that the baking time may vary depending on your oven and the baking dish you use. Keep checking every couple of minutes after the 25 minute mark to make sure it doesn’t start to burn around the edges. You know the cake is ready when it’s firm to the touch and a toothpick comes out clean when you test it.
Allow the polenta cake to cool for at least 10 minutes, then serve!