Preheat the oven to 160° Fan and line a 9-inch (20cm) round baking tin with baking paper, and grease with a greasing brush.
Cream together the butter and sugar before adding in the lemon zest and creaming again.
200 g fine caster sugar, 115 g unsalted butter, zest of 1 lemon
Whisk in the eggs one at a time until thoroughly combined.
2 medium eggs
In a separate bowl, whisk together the flour, ground almonds, baking powder, salt and Xanthan Gum.
260 g gluten-free plain flour blend, 3 tbsp ground almonds, 2 tsp baking powder, ¼ tsp Xanthan Gum, ¼ tsp salt
Add the dry ingredients and the milk in alternate batches to the wet mixture, and mix until just combined, Be careful not to overmix.
160 ml milk
Pour half of the mixture into the round baking tin and level off with an offset spatula. Toss the fresh blueberries in some flour to coat them. Sprinkle a handful of blueberries onto the mixture in the baking tin.
100 g fresh blueberries
Transfer the left over mixture to the baking tin and level off with an offset spatula. Sprinkle the rest of the blueberries on top of the mixture, pressing them in slightly.
Bake on the middle shelf for around 50 minutes, or until an inserted toothpick comes out without any wet mixture on. After around 20 minutes of baking time, cover the cake with a layer of tinfoil so as to prevent it from over-browning.
Once baked, allow to cool slightly in the tin before removing and dusting with a layer of icing sugar or fine caster sugar.