Preheat your oven to 325 degrees F
Use 1 Tablespoon of butter to grease a bundt pan. Then, use 1 Tablespoon almond flour to dust the bundt pan. Shake off and discard the excess.
With an electric mixer, beat the eggs and the egg yolk together in a bowl, then set aside.
Place the softened butter in a large bowl, then mix it using an electric mixer for 1 minute.
Add in the caster sugar and mix for a few more minutes until pale and increased in volume.
Continue to beat the mixture as you slowly add the beaten eggs.
Once the eggs are well incorporated, add the orange juice, orange zest, and vanilla extract. Mix until well blended.
Add the almond flour, polenta, salt, and baking powder and fold through the mixture until well combined.
Transfer the batter into the bundt pan.
Place the pan in the oven and bake for 50-60 minutes.
When the cake is done, remove from the oven and set aside to cool.