To make the lemon butter beat the butter in the bowl of an electric mixer fitted with a paddle attachment until light and fluffy. Add the lemon zest and slowly add the icing sugar until soft and creamy. Remove from the mixing bowl and set aside.
To make the pancakes, add the caster sugar and eggs to the bowl of an electric mixer and whisk until light and frothy. Add the flour, sugar, buttermilk, vanilla and melted butter and mix until smooth. Fold through ¾ of the blueberries.
Heat a non-stick frying pan over a medium heat and lightly grease with butter or an oil spray and add ⅓ cup measures of the batter to the frying pan and cook for 2 minutes, or until bubbles form and the top is lightly set. Flip and cook for another 2 minutes.
Transfer the cooked pancakes to a preheated oven to keep warm while you cook the remaining pancakes.
Serve the pancakes with the lemon butter and fresh blueberries.