Preheat your oven to 350°F (175°C).

In a large mixing bowl, cream together the softened butter and sugar until light and fluffy (2-3 minutes).

Mix in the egg and vanilla extract until fully combined.

In a separate bowl, whisk together flour, baking powder, salt, and lemon zest.

Gradually mix the dry ingredients into the wet mixture until combined.

Using a cookie scoop or your hands, press about one tablespoon of dough into the bottom and up the sides of greased mini muffin tins.

Bake for 10-12 minutes until edges are light golden brown.

Allow the cookie cups to cool for 5 minutes before transferring to a wire rack.

Once cooled, fill each cup with lemon cream filling.