Instructions: Heat the oven to 350 degrees. Line 2 nonstick baking sheets with baking mats. Sift together flour, baking powder, and salt. Set aside.

In the bowl of an electric mixer fitted with a paddle attachment, cream the butter and 3/4 cup sugar until the mixture is light and fluffy. Add the vanilla, egg, milk, and lemon zest. Slowly add the dry ingredients. When well mixed, remove the dough from the bowl. Wrap the dough in plastic wrap and refrigerate until firm, about 1 hour.

Divide the dough into 4 equal parts. Roll out each piece of dough between two pieces of plastic wrap to form a rough circle, about 8 inches across and 1/4-inch thick. Peel off the top piece of plastic wrap, and use a pastry wheel to cut the circle into 6 equal wedges.

Using the back of the knife, mark each cookie with 3 or 4 lines radiating from the point of the triangle. Brush with egg white. Sprinkle each group of wedges with 1 tablespoon granulated sugar. Transfer to prepared baking sheets. Bake until crisp and golden brown, 10 to 12 minutes. Remove to a wire rack to cool.

This recipe yields 24 cookies.

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