Recipes: Lemon twinkle cookies

Ingredients

• 1⁄2 cup unsalted butter, at room temperature
• 1⁄2 cup granulated sugar
• 1⁄2 cup icing sugar, sifted
• 2 large egg yolks
• 1 tsp pure vanilla extract
• Finely grated zest of 1 lemon
• 3 tbsp freshly squeezed lemon juice
• 2 oz white couverture (baking) chocolate, melted and cooled to room temperature
• 11⁄2 cups all-purpose flour
• 2 tbsp cornstarch
• 1⁄2 tsp each: baking soda and baking powder
• White decorator’s or sanding sugar, or granulated sugar, for rolling