In a mixer bowl fitted with the paddle attachment, beat butter and powdered sugar on medium speed until light and fluffy, approximately 3 minutes.
Add in egg yolks, vanilla, and lemon zest. Mix until just combined. Reduce speed to low.
Sift and mix flour, cornstarch, baking powder, and baking soda in a separate bowl, and then add to the mixture. Process just until a uniform dough is obtained.
Flatten the dough into a disc and put it in a plastic bag/wrap. Refrigerate until 30 minutes.
Preheat oven to 350°F/180°C.
On a lightly floured surface (or between 2 pieces of parchment paper) roll the dough to a ¼-inch (½ cm) thickness. Cut into circles using a cookie cutter.
Place the cookies on a baking sheet lined with parchment paper and bake for 8-10 minutes, until the cookies begin to brown at the edges and are still very light in the center. Cool completely before filling.