01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - In a large bowl, beat softened butter and granulated sugar until light and fluffy, approximately 2-3 minutes.
03 - Mix in egg, lemon juice, lemon zest, and vanilla extract until fully incorporated.
04 - In a separate bowl, whisk together flour, baking soda, salt, and poppy seeds until evenly distributed.
05 - Gradually add dry ingredients to wet mixture, stirring until just combined. Avoid overmixing.
06 - Drop rounded tablespoons of dough onto prepared baking sheets, spacing 2 inches apart to allow for spreading.
07 - Bake for 10-12 minutes until edges are lightly golden. Centers should appear slightly underbaked.
08 - Let cookies rest on baking sheet for 2 minutes, then transfer to wire rack to cool completely.
09 - Whisk powdered sugar with lemon juice until smooth. Drizzle over cooled cookies and allow glaze to set before serving.