Soften butter and mix with icing sugar until the mixture turns pale
Gradually add egg whites in three parts, mixing well after each addition
Add sifted low-gluten flour and cornstarch, stirring until well combined
Place the cookie dough into a piping bag and squeeze it into molds, smoothing the surface with a spatula
Preheat oven to 150°C (302°F) and bake for 10 to 12 minutes
Melt white chocolate and squeeze it into molds, then refrigerate until solidified
Place a small amount of melted chocolate between cookies and lightly press to sandwich the two cookies together
