Prep time 10 minutes
Cook time 20 minutes
Preheat oven to 350ºF.
Beat butter and sugar until light, using an electric mixer; beat in egg yolks and vanilla. In a separate bowl, combine flour and poppy seeds. Add to butter mixture, mixing until just blended.
Shape dough into 1-inch balls. Place 1 inch apart on lightly greased baking sheets. Make a deep indentation in center of each ball. Bake for 20 minutes.
Transfer from baking sheets to wire racks; cool completely. Spoon lemon curd into centers of cookies; dust with powdered sugar.