Add a burst of citrus flavor to your cookie jar with these delightful lemon curd thumbprint cookies. The cookie dough is made by creaming together butter, sugar, and vanilla extract, then gradually adding flour until a soft dough forms. Roll the dough into small balls, make an indentation in the center of each cookie with your thumb, and fill it with a spoonful of lemon curd. Bake the cookies until golden brown and let them cool before enjoying. These lemon curd thumbprint cookies are perfect for tea time or as a sweet treat any time of the day.