Begin by melting the butter in a microwave-safe bowl or on the stovetop over low heat. Once melted, allow it to cool to room temperature.

In a large mixing bowl, combine granulated sugar with lemon zest. Rub the two together until fragrant.

Add the cooled melted butter, egg, and vanilla extract to the sugar and zest mixture. Blend until smooth.

In a separate bowl, whisk together the all-purpose flour, baking powder, baking soda, poppy seeds, and salt.

Carefully add the dry ingredients to the wet ingredients and mix until just combined.

Scoop the cookie dough into balls and refrigerate for 30 minutes.

Preheat your oven to 180ºC (355ºF).

Remove dough from the refrigerator and place on a lined baking sheet. Bake for 10-11 minutes.

In another bowl, beat together cream cheese, powdered sugar, vanilla extract, and heavy cream until stiff peaks form.

Once the cookies are cooled, frost each one generously with the cheesecake frosting.