These lemon curd thumbprint cookies are a delightful combination of buttery shortbread and tangy lemon curd. The cookie dough is made with butter, sugar, flour, and a hint of vanilla extract. After shaping the dough into small balls, a thumbprint is made in the center of each cookie, which is then filled with a spoonful of lemon curd. The cookies are baked until golden and the lemon curd is slightly set. Enjoy these sweet and citrusy treats with a cup of tea or coffee.