01 - Preheat oven to 350°F. Grease and flour a 12-cup Bundt pan thoroughly to ensure proper cake release.
02 - In a medium bowl, whisk together flour, poppy seeds, baking powder, baking soda, and salt until evenly distributed.
03 - In a large bowl, beat softened butter and granulated sugar with an electric mixer until light and fluffy, approximately 3 minutes.
04 - Add eggs one at a time, beating thoroughly after each addition. Mix in lemon zest, lemon juice, and vanilla extract until fully combined.
05 - In a separate bowl, whisk together whole milk and sour cream until smooth and homogeneous.
06 - With mixer on low speed, alternately add flour mixture and milk mixture to the butter mixture, beginning and ending with the flour. Mix just until combined without overmixing.
07 - Transfer batter evenly into the prepared Bundt pan. Smooth the top surface for even baking.
08 - Bake for 45 to 55 minutes, or until a toothpick inserted into the center comes out clean with no wet batter.
09 - Allow cake to cool in the pan for 15 minutes, then invert onto a wire rack to cool completely before glazing.
10 - Whisk powdered sugar, fresh lemon juice, and lemon zest until smooth and pourable, adjusting consistency as needed.
11 - Drizzle glaze evenly over the cooled cake and allow it to set for several minutes before slicing.