Step 2: In a medium bowl, whisk together the all-purpose flour and fine sea salt. Set aside. In a large mixing bowl, cream the softened unsalted butter and granulated sugar until light and fluffy, about 3 to 4 minutes. Add lemon zest and vanilla extract, mixing well. Gradually add the flour mixture, stirring until just combined.
Step 3: Scoop about a tablespoon of dough, roll into a ball, and place on ungreased baking sheets. Make an indentation in each ball with your thumb.
Step 4: Fill each indentation with a small spoonful of prepared lemon curd.
Step 5: Bake for about 12 to 15 minutes, or until the edges are lightly golden.
Step 6: Remove from the oven and let cool on baking sheets for about 5 minutes before transferring to wire racks to cool completely.
Notes
Make sure your butter is really softened for a fluffy texture. Let the cookies cool slightly before transferring to avoid breaking.