01 - Preheat the oven to 350°F. Grease a 9x5-inch loaf pan and line with parchment paper.
02 - In a medium bowl, whisk together flour, baking powder, baking soda, salt, and poppy seeds until well blended.
03 - In a large bowl, whisk sugar and eggs until thick and pale, about 2 minutes. Add milk, melted butter, lemon juice, lemon zest, and vanilla extract; whisk until smooth and fully incorporated.
04 - Gently fold the dry ingredients into the wet mixture using a rubber spatula until just combined. Do not overmix to ensure a tender crumb.
05 - Pour the batter into the prepared loaf pan and smooth the top with an offset spatula.
06 - Bake for 45-55 minutes, or until a toothpick inserted into the center comes out clean and the top is golden brown.
07 - Let the loaf cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before glazing.
08 - In a small bowl, whisk together powdered sugar and enough lemon juice to make a thick, pourable glaze. Adjust consistency as needed.
09 - Drizzle the glaze over the cooled loaf. Allow it to set for 15-20 minutes before slicing and serving.