Preparation

1. In a large mixing bowl, whisk together flour, baking powder and salt. Reserve.2. With a vegetable peeler, remove the peel of half the lemon, being very careful not to include any of the bitter white pith. Put the lemon peel and sugar into the blender jar. Secure lid.3. Select Speed 10 and press Start. Blend until lemon peel is finely chopped, about 4 seconds.4. Juice the lemon. Add 1½ tablespoons of the freshly squeezed lemon juice, egg, milk and butter into the blender jar with the lemon zest and sugar. Secure lid. Select Speed 5 and press Start. Blend until smooth, about 6 seconds.5. Add liquid mixture to the dry ingredients in the large mixing bowl; gently mix by hand until smooth.6. Form dough into a disc and wrap in plastic wrap. Refrigerate until chilled, at least 3 hours and up to 1 week.7. To bake cookies, preheat oven to 425°F. While oven is heating, roll dough into a ¼-inch-thick layer.8. Cut cookies with a cookie cutter of your choice and arrange on a baking sheet lined with parchment paper. Sprinkle with sugar.9. Bake cookies until golden, about 5 to 7 minutes or longer if cookies are larger than 1½ inches.10. Let cool on pan for 1-2 minutes, then transfer to a wire rack to cool completely before serving.