Grease a 9 inch cake tin with butter. Preheat the oven to 180 degrees celsius.
Add the butter and sugar to a large bowl and cream together until light and fluffy. Crack in the eggs one at a time, beating to thoroughly combine after each one.
Add the flour, polenta and wild strawberries. Fold in until fully mixed (but don't over mix).
Tip the batter into the cake tin and put in the oven for 30 minutes or until a skewer inserted into the centre of the cake comes out clean. Leave to cool before eating.