01 - Preheat oven to 350°F (175°C). Generously grease and flour a 10 to 12-cup Bundt pan, coating all crevices thoroughly.
02 - Whisk together flour, baking powder, baking soda, salt, and poppy seeds in a medium bowl. Set aside.
03 - Beat softened butter and granulated sugar on medium speed until light and fluffy, about 3 to 4 minutes, using a stand or hand mixer.
04 - Add eggs one at a time, mixing well after each addition. Stir in lemon zest and vanilla extract until combined.
05 - Combine fresh lemon juice and whole milk in a measuring cup.
06 - With mixer on low speed, alternately add the flour mixture and lemon-milk mixture to the batter, beginning and ending with flour. Mix until just combined to avoid overmixing.
07 - Pour batter evenly into the prepared Bundt pan. Smooth the surface with a spatula.
08 - Bake for 45 to 55 minutes, or until a skewer inserted into the center comes out clean.
09 - Let cake cool in the pan for 15 minutes. Carefully invert onto a wire rack and cool completely.
10 - Whisk powdered sugar, lemon juice, and lemon zest until smooth and pourable.
11 - Drizzle glaze evenly over cooled cake. Allow glaze to set before slicing and serving.