01 -
Preheat your oven to 350°F (180°C). Line a 12-cup muffin tin with paper liners. Wash the lemon thoroughly, then zest the entire peel and squeeze to extract the juice, setting aside both for the batter and glaze.
02 -
In a large bowl, sift together the flour and baking powder to remove any lumps. Add the granulated sugar and vanilla sugar, whisking to combine evenly.
03 -
Make a well in the center of the dry ingredients. Pour in the oil, sparkling mineral water, 2 tablespoons of the lemon juice, and all of the lemon zest. Stir just until combined and no dry spots remain - the batter will be somewhat thick but should flow easily. Divide the batter evenly among the muffin cups, filling each about 2/3 full.
04 -
Bake in the preheated oven for 25-30 minutes, until the tops are lightly golden and a toothpick inserted into the center comes out clean. Allow to cool in the pan for 5 minutes before transferring to a wire rack to cool completely.
05 -
Once the muffins are completely cool, prepare the glaze by whisking together the powdered sugar and remaining lemon juice until smooth. If needed, add a few more drops of lemon juice to reach your desired consistency. Spoon or brush the glaze over the tops of each muffin, allowing it to drip slightly down the sides.