Make the Lemon Curd:

1. In a small saucepan, whisk together the eggs, sugar, and lemon juice. Cook over medium heat, stirring constantly, until the mixture thickens (about 5–7 minutes).
2. Remove from heat and stir in butter and lemon zest until smooth. Transfer to a bowl, cover with plastic wrap (pressing it directly onto the surface), and refrigerate until chilled.

Make the Cookies:

1. Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper.
2. In a large mixing bowl, cream the butter and sugar together until light and fluffy. Add the egg yolks and vanilla extract, mixing until combined.
3. Gradually add the flour and salt, mixing until a soft dough forms.
4. Roll the dough into 1-inch balls and place them on the prepared baking sheets, spacing them about 2 inches apart.
5. Use your thumb or the back of a small spoon to create an indentation in the center of each ball.

Bake:

1. Bake for 10–12 minutes, or until the edges are lightly golden. If the indentations puff up during baking, gently press them back down with the back of a spoon while the cookies are still warm. Allow the cookies to cool completely on the baking sheet.

Fill the Cookies:

1. Once the cookies are cooled, fill each indentation with a small spoonful of lemon curd. Smooth the tops with the back of a spoon if needed.

Optional Finishing Touch:

• Dust the cookies with powdered sugar for a decorative finish.