Preheat your oven to 350°F (175°C). This ensures your cookie cups start baking at the optimal temperature for that perfect texture.

Cream together the butter, sugar, and lemon zest until fluffy. This should take about 2-3 minutes and results in a light, airy mixture that’s full of citrus aroma.

Add the eggs one at a time, mixing well after each addition. Incorporate the vanilla extract and salt, enriching the flavor and creating a well-blended batter.

Whisk together the baking powder, baking soda, and flour in a separate bowl. Gradually incorporate this dry mixture into the buttery mixture, ensuring no pockets of flour remain.

Scoop 1-inch balls of dough into a greased mini muffin tin. Gently press down to form little cups, ensuring the shape holds during baking.

Bake for 7-8 minutes, until lightly golden. Allow them to cool for about 5 minutes in the tin before transferring to a cooling rack.

For the Lemon Curd: Blend the lemon juice, egg yolks, sugar, cornstarch, and lemon zest until smooth.

Cook the mixture over medium heat, stirring continuously, until it reaches a rapid boil.

Remove from heat and whisk in the cold, cubed butter until completely smooth.

Fill each cooled cookie cup generously with the lemon curd. Refrigerate until chilled.

Dust with powdered sugar before serving for a lovely, finishing touch.