Preheat oven to 200°C bake / 180°C fan bake. Line a 12-hole muffin tin with paper cases (or grease well).
Place milk, Chelsea Caster Sugar, oil, egg, lemon zest and lemon juice in a large bowl. Whisk to combine well.
Sift flour and baking powder over the top. Fold in until just combined and moistened. Gently fold in blueberries (don't over mix or the muffins will be tough and won't rise evenly).
Divide mixture evenly between paper cases. Bake for 17-20 minutes, until muffins are golden and spring back when lightly pressed on top. Transfer to a wire rack to cool. Dust with Chelsea Icing Sugar to serve, if desired.
