01 - Preheat oven to 350°F. Thoroughly grease and flour a bundt pan to ensure easy release after baking.
02 - Whisk flour, poppy seeds, baking powder, baking soda, and salt in a medium bowl until evenly distributed.
03 - Beat butter and sugar with electric mixer on high speed for 3 minutes until pale, light, and fluffy.
04 - Add eggs one at a time, mixing completely after each addition. Blend in lemon zest, lemon juice, and vanilla extract.
05 - On low speed, alternately add flour mixture and sour cream, starting and ending with flour. Pour in milk and mix until just incorporated.
06 - Transfer batter to prepared pan, smooth surface, and bake for 45-50 minutes until toothpick inserted in center emerges clean.
07 - Let cake rest in pan for 15 minutes, then carefully invert onto wire rack to cool completely.
08 - Whisk powdered sugar with lemon juice until smooth and drizzling consistency is reached.
09 - Drizzle glaze evenly over completely cooled cake. Allow glaze to set before slicing.