In a small saucepan, combine fresh lemon juice, lemon zest, egg yolks, granulated sugar, and a pinch of salt.

Place the saucepan over medium-low heat, whisking constantly for 20 to 25 minutes until thickened.

Remove from heat and whisk in cold, cubed butter until smooth. Cover with plastic wrap touching the surface to prevent a skin from forming. Allow to cool completely.

Whisk together the all-purpose flour, baking powder, and fine salt in a mixing bowl.

In another bowl, cream softened butter and granulated sugar using a mixer until light and fluffy.

Add egg yolk, vanilla extract, and finely grated lemon zest. Mix until fully incorporated.

Gradually add in the dry ingredients using a spatula and mix until just combined. Cover the dough and refrigerate for about an hour.

Preheat your oven to 350°F (175°C).

Scoop chilled dough into 1-inch balls and place them on prepared baking sheets, spacing them 2 inches apart.

Create a shallow well in the center of each ball of dough. Bake for about 10 minutes until edges are lightly golden.

Once out of the oven, spoon about 1 teaspoon of lemon curd into each well while warm. Allow cookies to cool completely on the baking sheet.