01 - Preheat oven to 350°F. Grease a 9x5-inch loaf pan and line with parchment paper.
02 - Whisk together flour, baking powder, baking soda, salt, and poppy seeds in a medium bowl until well combined.
03 - Beat softened butter and granulated sugar with an electric mixer on medium speed until light and fluffy, approximately 2-3 minutes.
04 - Add eggs one at a time, mixing thoroughly after each addition. Blend in lemon zest, lemon juice, sour cream, milk, and vanilla extract until smooth.
05 - Gradually fold dry ingredients into wet mixture using a rubber spatula until just incorporated. Take care not to overmix.
06 - Toss fresh raspberries with 1 tablespoon flour in a small bowl until evenly coated. Gently fold floured berries into the batter.
07 - Spoon batter into prepared loaf pan, using spatula to smooth and level the top surface evenly.
08 - Bake for 50-60 minutes until a toothpick inserted into the center emerges clean. Tent loosely with aluminum foil after 35 minutes if top browning too rapidly.
09 - Allow loaf to rest in pan for 15 minutes. Remove from pan and transfer to wire rack to cool completely before glazing.
10 - Whisk powdered sugar and fresh lemon juice in a small bowl until smooth and drizzleable. Pour over completely cooled loaf.