Preheat the oven to 325ºF (160ºC) and line a baking sheet with parchment paper.
In a medium-sized bowl, whisk together the flour, poppy seeds, salt, and lemon zest. Set aside.
In a second, larger bowl, use a hand or stand mixer to cream together the butter and sugar until light and fluffy, about 2 to 3 minutes.
Use a fine mesh sieve to sift the flour into the butter. Mix everything together on low until the dough starts to clump together. It may take a little while for the dough but I promise you it will! You can stop mixing when the cookie dough forms larger clumps, about the size of popped popcorn.
Gather the cookie dough together in the bowl with your hands and place it on a work surface. Divide the dough into 12 equal portions (approximately 33 g each). Sprinkle 1 tablespoon of sugar on a small plate. Roll each cookie dough portion into a smooth ball between your hands. Place the dough balls, a few at a time, on the plate of sugar. Swirl the plate in gentle circles. The balls will roll around and become sugar coated as you swirl the plate.
Space the 12 cookie dough balls evenly apart on the prepared baking sheet. Using a ceramic cookie stamp, or the bottom of a drinking glass, gently press and flatten the top of each dough ball to about 2 ½ inches (6 ½ cm) in diameter and ¼ inch (6 mm) thick. Place the cookies in the preheated oven and bake them for 26 to 28 minutes, or until the tops are pale and the edges are light gold. Remove the cookies from the oven and immediately transfer them from the baking sheet to a wire rack to cool.
Notes
To make lemon poppy seed shortbread cookies, you can use a hand mixer, stand mixer, or go the traditional route and use elbow-grease and a wooden spoon. Choose whichever tool works for you!Add ½ teaspoon of vanilla or lemon extract to the butter and sugar before mixing if you like.If you don't own cookie stamps, I talk about them a bit more here in this stamped brown sugar shortbread post.You can divide the cookie dough into 24 smaller portions rather than 12 if you like, however the baking time will change. Just watch for light golden edges and you should be good.Rolling the dough balls in sugar is completely optional. If you don't want the extra sugar, simply sprinkle a bit of flour on each dough ball, or dip your stamp / the bottom of your glass in flour, before flattening the lemon poppy seed shortbread cookies.The edges of the cookies should crack as you stamp / flatten the dough balls. The cracking is an indication of a correct butter-to-flour ratio.Skip the cookie stamp and instead use a flat-bottomed drinking glass to flatten the lemon poppy seed shortbread cookies. When fully cooled, top them with this luscious whipped cream cheese frosting.Lemon poppy seed shortbread cookies will keep in an airtight container at room temperature for up to one week.To freeze, gently place the fully-cooled cookies in a sealed zip-top plastic bag in the freezer for up to two months.
Substitutions
Because lemon poppy seed shortbread cookies is a pretty basic recipe with very few ingredients, there aren't a whole lot of substitutions you can make. That being said, orange zest in place of lemon zest would be dreamy.Use a high-quality dairy-free butter to make vegan lemon poppy seed shortbread cookies.Another shaping option is to roll the cookie dough into a log-shape. Wrap the log in wax paper and store it in the fridge or freezer. To bake, simply slice ¼ inch (6 mm) thick discs from the log, and bake them as per the recipe directions.