01 - Preheat oven to 350°F. Thoroughly grease and flour a 10-cup bundt pan, ensuring all crevices are coated to prevent sticking.
02 - In a medium bowl, whisk together flour, baking powder, baking soda, salt, and poppy seeds until evenly distributed. Set aside.
03 - In a large bowl, beat butter, sugar, and lemon zest with an electric mixer on medium-high speed until light and fluffy, approximately 3 minutes.
04 - Add eggs one at a time, beating well after each addition until fully incorporated. Mix in vanilla extract.
05 - In a measuring cup, combine whole milk and fresh lemon juice. Stir briefly and set aside.
06 - With mixer on low speed, alternately add the flour mixture and milk mixture to the butter mixture, beginning and ending with the flour. Mix until just combined; avoid overmixing to prevent tough texture.
07 - Pour batter into prepared bundt pan and smooth the top. Bake for 45-55 minutes, or until a toothpick inserted in the center comes out clean.
08 - Allow cake to cool in the pan for 15 minutes, then carefully invert onto a wire rack to cool completely.
09 - Whisk powdered sugar with 2 tablespoons lemon juice until smooth. Add additional lemon juice as needed to achieve a thick but pourable consistency.
10 - Drizzle icing evenly over the cooled cake. Sprinkle with additional lemon zest if desired. Allow icing to set for 15-20 minutes before slicing and serving.