Preheat the oven to 180°C/fan 160°C/gas mark 4. Grease a 2lb loaf tin and line with baking paper.
Using an electric hand mixer, cream the butter and sugar together in a bowl until soft and pale. Beat in the eggs, one at a time, adding 1 tbsp ground almonds with each egg.
Stir through the polenta, lemon juice and zest, baking powder and remaining ground almonds, then stir in the yogurt and half the blueberries.
Pour into the loaf tin and scatter the remaining blueberries over the top, lightly pressing into the mixture. Bake for 45 minutes, or until a skewer inserted into the centre comes out clean.