Step 1In a medium bowl, whisk together the powdered sugar, lemon juice and corn syrup. Whisk in milk to make a thick, spreadable icing. If coloring the icing with liquid food coloring, you might want to add a little less milk as the coloring will dilute the frosting. For different flavors, add drops of vanilla, almond or lemon extract. For shinier icing, use a little more corn syrup and a little less milk. The frosting will keep, tightly covered and refrigerated, for up to 1 week.
Step 1In the bowl of a stand mixer, or in a large bowl using an electric mixer, beat the butter and sugar until light and creamy, 3 to 5 minutes. Beat in the eggs and egg yolks, one at a time, until combined, then beat in the vanilla and almond extracts.
Step 2In a separate large bowl, sift together the flour, salt and baking powder. Slowly beat the flour mixture in with the butter mixture until combined to form a smooth dough.
Step 3Wrap the dough in plastic wrap and refrigerate overnight, or until well chilled.
Step 4Heat the oven to 350 degrees. On a floured surface, roll the dough to a thickness of about one-eighth inch. Cut out cookie shapes from the dough. Space the cookies about 1 inch apart on a baking sheet and bake until lightly browned, 6 to 8 minutes.
Step 5Remove from the sheets and cool completely before icing. Ice as desired.