01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together flour, baking powder, baking soda, salt, and poppy seeds.
03 - In a large bowl, cream together the butter and sugar until light and fluffy, about 2 minutes.
04 - Beat in the egg, lemon zest, lemon juice, and vanilla extract until combined.
05 - Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix.
06 - Scoop tablespoon-sized balls of dough onto the prepared baking sheets, spacing them about 2 inches apart.
07 - Bake for 10 to 12 minutes, or until the edges are lightly golden. Let cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.
08 - In a medium bowl, beat cream cheese and butter together until smooth. Add powdered sugar, lemon juice, vanilla, and salt. Beat until light and fluffy.
09 - Once cookies are completely cool, spread or pipe a generous layer of cheesecake frosting onto each cookie.
10 - Optionally, garnish with extra lemon zest or a sprinkle of poppy seeds.