New York Black and White Cookies

• ¼ organic lemon, thin peel only, no white pith
• 5 ½ oz sugar
• 3 ½ oz unsalted butter, soft, cut into pieces
• 1 - 2 tsp vanilla extract
• ¼ tsp almond extract (可省略)
• 2 large eggs
• 2 oz whole milk
• 7 oz all-purpose flour
• 2 oz corn starch
• 1 tsp baking powder
• 1 pinch salt

Icing

• 14 oz confectioners sugar
• 2 oz water, plus 1-3 tsp extra to thin chocolate icing, if necessary
• 1 tsp corn syrup
• ½ tsp natural vanilla extract
• 4 tbsp dutch-processed cocoa powder