01 - Preheat oven to 350°F. Thoroughly grease and flour a 10-12 cup bundt pan, ensuring all crevices are coated for easy release.
02 - In a medium bowl, whisk together flour, baking powder, baking soda, salt, and poppy seeds until evenly distributed. Set aside for later use.
03 - In a large bowl, beat softened butter and granulated sugar with electric mixer on medium-high speed for approximately 3 minutes until mixture appears light, pale, and fluffy.
04 - Add eggs individually, beating thoroughly after each addition until fully incorporated. Blend in lemon juice, lemon zest, and vanilla extract until combined.
05 - With mixer on low speed, add flour mixture in three portions, alternating with sour cream and milk. Begin and end with flour addition, mixing only until ingredients are just incorporated. Avoid overmixing to prevent tough texture.
06 - Spoon batter into prepared bundt pan, distributing evenly. Smooth surface with spatula to ensure uniform baking.
07 - Place pan in preheated oven and bake for 45-50 minutes. Test doneness by inserting skewer into center of cake; it should emerge clean or with minimal moist crumbs.
08 - Allow cake to rest in pan for 15 minutes before carefully inverting onto wire rack. Cool completely to room temperature before applying glaze.
09 - Whisk sifted powdered sugar, lemon juice, and lemon zest in small bowl until mixture achieves smooth, pourable consistency. Add additional lemon juice if glaze appears too thick.
10 - Drizzle prepared glaze evenly over cooled cake. Allow glaze to set completely at room temperature before slicing and serving.