01 - Preheat the oven to 350°F. Grease and flour a 9×5-inch loaf pan, or line it with parchment paper, leaving an overhang on the sides for easy removal.
02 - In a large mixing bowl, beat the softened butter and granulated sugar together using an electric mixer on medium-high speed until pale, light, and fluffy—about 3 to 4 minutes.
03 - Add the eggs one at a time, beating well after each addition until fully incorporated before adding the next. Scrape down the sides of the bowl as needed.
04 - Pour in the whole milk, fresh lemon juice, and lemon zest. Stir until just combined. The batter may appear slightly curdled—this is normal and will resolve when the dry ingredients are added.
05 - In a separate medium bowl, whisk together the all-purpose flour, baking powder, kosher salt, and poppy seeds until evenly distributed.
06 - Gradually add the dry ingredient mixture to the wet batter in three additions, folding gently with a spatula after each. Mix only until just incorporated—do not overmix to keep the crumb tender.
07 - Pour the batter into the prepared loaf pan and use a spatula to smooth the top into an even layer. Tap the pan gently on the counter to release any trapped air bubbles.
08 - Bake on the center rack for 35 to 40 minutes, or until the top is golden brown and a toothpick inserted into the center comes out clean. Rotate the pan halfway through baking for even browning.
09 - Remove from the oven and let the cake cool in the pan for 10 minutes. Then use the parchment overhang to lift it out and transfer to a wire rack to cool completely.
10 - In a small bowl, whisk together the sifted powdered sugar and fresh lemon juice until smooth and drizzle-able. Once the cake has cooled completely, drizzle the glaze evenly over the top, allowing it to cascade down the sides. Let the glaze set for 10 minutes before slicing.