01 - Preheat oven to 350°F and line two baking sheets with parchment paper for easy cleanup and even baking.
02 - In a medium bowl, whisk together flour, baking powder, baking soda, salt, and poppy seeds until thoroughly blended. Set aside for later use.
03 - In a large bowl, beat softened butter, granulated sugar, and lemon zest on medium-high speed for 2-3 minutes until mixture appears pale, light, and fluffy.
04 - Add the egg, vanilla extract, and fresh lemon juice to the butter mixture. Mix on medium speed until fully combined and smooth.
05 - Gradually add the dry ingredient mixture to the wet ingredients, mixing on low speed just until no flour streaks remain. Cover bowl and refrigerate dough for 15 minutes to firm slightly for easier handling.
06 - In a separate bowl, beat cream cheese, powdered sugar, and vanilla extract until completely smooth and creamy. Refrigerate filling until ready to assemble cookies.
07 - Scoop 1½ tablespoons of chilled dough, flatten into a disc in your palm, and place 1 teaspoon of cheesecake filling in the center. Top with another tablespoon of dough, carefully seal edges to encase filling, and gently roll into a smooth ball.
08 - Roll each assembled dough ball in granulated sugar, pressing gently to adhere coating. Optionally roll in extra poppy seeds for additional crunch. Place coated balls on prepared baking sheets, leaving 2 inches of space between each cookie.
09 - Bake cookies for 12-14 minutes until edges are lightly golden and centers appear set. Remove from oven and let cookies rest on baking sheet for 5 minutes to firm before transferring to wire rack to cool completely.