Preheat the oven to 350˚F. (177˚C.) Line two baking sheets with parchment paper. Set aside.

In a medium size bowl, combine the soft butter and sugar. Stir until smooth and well combined.

Add the egg yolks, vanilla extract and lemon zest. Stir to combine. Add the flour and stir until well incorporated and the dough starts to come together. The mixture will seem crumbly at first. Just keep stirring until it comes together.

Sprinkle a work surface with flour. Have some extra flour on the side in a small cup.

Turn the dough over several times to coat lightly with the flour then divide the dough in two and cover one half with a piece of plastic wrap.

Keeping the surface and your rolling pin lightly dusted with flour at all times, roll out the dough to the desired thickness. I like mine about a ¼ thick for thinner cookies and closer to ⅜ for thicker ones. You can go thinner or thicker it’s just important to keep the surface underneath the dough lightly floured as you roll. (I also like to dip my cookie cutter in flour before cutting each cookie to keep the dough from sticking to the cutter.)

Use a cutter of your choice (I used a scalloped 2.5-inch cutter) to cut out the cookies, transferring them to one of the prepared sheet pans as you go. Space the cookies 2 inches apart.

Bring the dough scraps together then roll out more cookies until the dough is used up. Repeat with second ball of dough. Chill the cookies in the refrigerator for 30 minutes before baking.

Bake the cookies for 12-16 minutes or until light golden brown. If the cookies have puffed a bit or have some little bubbles, you can flatten them at this point with the back of a flat metal spatula. Transfer the cookies to a wire cooling rack to cool completely.

Combine powdered sugar, lemon juice, 1 tablespoon half and half and vanilla extract in a medium-size bowl. Mix until smooth. The glaze should be fairly thick, but pourable. Add a little more half and half if too thick. Add more powdered sugar if it’s too thin. (See picture above in the post.)

Transfer the glaze to a small shallow bowl (a little larger than your cookies). Slowly stir the glaze to release and air bubbles.

Holding onto the edges of one cookie, dip the top surface into the glaze, being sure all of the surface touches the glaze. Pull cookie straight up out of the glaze and allow excess glaze to drip into the bowl for about 15-20 seconds. (You can gently shake the cookie back and forth and up and down to get it to drip a little faster.) Then quickly flip the cookie to the right side up and give it a gentle jiggle to allow the glaze to flow evenly over the surface. If the glaze drips over the edge of the cookie, you didn’t let it drip quite long enough.

Repeat the dip, drip and flip technique with the remaining cookies. Place cookies on a cooling rack and allow the glaze to dry for 20-30 minutes. If you want to stack the cookies in a storage container or box for gifting, you’ll need to let the glaze dry for at least 8 hours. I like to let them sit out overnight before stacking.

Store in an airtight container. These cookies actually keep well for several weeks once the glaze is set and dry.