Step 1 Combine butter, 1 ¼ C. powdered sugar, and lemon zest in the bowl of your stand mixer. You can use a bit more zest or lemon juice if you want to give your cookies a stronger lemon flavor. At the listed amounts, the lemon flavor is wonderfully subtle. Use the paddle attachment. Mix at a low speed until the sugar is moistened. Turn the mixer speed to medium-high and continue to beat for about 3 minutes. You want the mixture to be a lighter color and to become aerated and fluffy.

Step 2 Scrape the sides of the bowl and mix in the lemon juice and the egg yolk. Continue to mix to combine.

Step 3 With your mixer set on a low speed, add the flour, cornstarch and salt. Mix just until the ingredients are combined.

Step 4 Divide your cookie dough into two equal parts and scrape it onto lengths of plastic wrap or parchment paper. Wrap the wrap around the dough and form it into a cylinder. You want the wrapped dough cylinder to be approximately 1 ½ inches wide. Rolling the cylinder on your counter will help round it. Chill. The original recipe says to chill the dough for at least 2 hours. I chilled my dough overnight.

Step 5 To bake the cookies, heat your oven to 350 degrees F. Line two large cookie sheets with parchment or a baking liner like a Silpat.

Step 6 Slice the dough into ¼ inch rounds. Place the cookies about 1 inch apart on your cookie sheets. Bake. My cookies took about 15 minutes to bake, but, of course, ovens vary. Watch your cookies carefully for the first batch. You want the cookies to be slightly brown on the edges and the bottom.

Step 7 Remove cookies from the oven and cool on a rack. Dust cookies with powdered sugar. These cookies will keep their crisp texture for several days when stored in an airtight container.