4 1/2 tablespoons unsalted butter, at room temperature
1/2 cup plus 2 tablespoons confectioners’ sugar
1 teaspoon granulated sugar + 1/2 teaspoon vanilla extract (to mimic 1 teaspoon of vanilla sugar that can only be found in France)
1 large egg white, at room temperature
1/2 cup plus 2 tablespoons cake flour
Cut butter into small pieces and place into a large bowl. Stir the butter with a wooden spoon and lightly whisk until creamy. Whisk or stir in confectioners’ sugar until fully incorporated with the butter. Stir until combined. Add granulated sugar and vanilla extract, again mixing well, before stirring in the egg white. Whisk everything together.
Sift cake flour into the mixture. Stir with a wooden spoon until combined and batter is smooth.
Preheat oven to 325 degrees. Line two baking sheets with parchment paper. Transfer batter to a piping bag fitted with a plain tip about 1/4 to 1/5 inch wide. Pipe 2 1/3 inch long strips on the lined baking sheets, leaving space between each to allow spreading.
Bake for approximately 12 minutes, until the biscuits are golden. Remove from the oven and allow biscuits to cool before removing with a spatula and transferring to a wire rack.
You can dip the biscuits in dark, milk, or white chocolate.
Melt 1 cup of white chocolate chips with 2 tb spoon of vegetable oil (or shortening) in a bain marie until melted; stir until smooth. Divide the melted chocolate into 3-4 bowls and add 1-2 drops of food coloring. Dip half of each cooled cookie into the melted chocolate. Place on waxed paper until chocolate is set.