Add the granulated sugar into a small bowl. Add 3 teaspoons grated lemon zest to the sugar. Stir to combine to infuse the sugar with lemon flavour.

With an electric mixer at medium speed, beat eggs, lemon infused sugar and vanilla until creamy.

Into a medium bowl sift the flour and salt. With the mixer on low speed, gradually add sifted flour, beating until blended, scraping down the sides as necessary.

Increase mixer speed to medium, slowly add melted butter while beating until combined and the batter is smooth and thick. Cover the bowl and chill batter in refrigerator for at least 30 minutes or overnight.

Meanwhile, preheat oven to 350 degrees F. Brush the insides of the indentations of a Madeleine pan with melted butter. Unless you have two pans, you will have to bake in two batches.

Spoon about 2 level tablespoons of batter into each indentation. No need to spread the batter as it will fill the mold as it bakes. Set aside remaining batter. Bake for 8 - 12 minutes (time will depend on the type of pan being used) until puffed and just lightly golden on the edges. Cool in pan for 1 minute. Gently remove Madeleines from the pan on to a rack to cool completely.

Lemon Glaze: In a small bowl, mix the icing sugar and lemon juice until smooth. Lightly brush the glaze on the patterned side of each Madeleine and sprinkle the cookies evenly with 4 teaspoons lemon zest. Place the cookies on a rack to set. Serve at room temperature.