Preheat the oven to 200 degrees C. Lightly coat a 12-hole muffin tray with cooking spray. Mix together the flour and caster sugar in a large bowl. Whisk the milk, eggs, fromage frais and vanilla essence in another bowl until blended.
Make a well in the centre of the flour mixture. Pour in the milk mixture and stir with a fork just until blended. Fold in two-thirds of the blueberries.
Spoon the mixture into the muffin tray and sprinkle evenly with the remaining blueberries. Bake for about 25 minutes or until a skewer inserted in the centre of a muffin comes out clean. Cool the muffins on a wire rack for 10 minutes.
Meanwhile, mix the icing sugar with the lemon zest and enough milk in a small bowl to make a glaze that will coat the back of the spoon. Drizzle the glaze over the muffins.