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.
03 - Beat butter and sugar with electric mixer until light and fluffy, about 2-3 minutes.
04 - Beat in eggs one at a time. Mix in lemon zest, lemon juice, sour cream, milk, and vanilla until fully combined.
05 - Gradually fold dry ingredients into wet mixture until just combined. Avoid overmixing.
06 - Toss raspberries with 1 tablespoon flour to prevent sinking, then gently fold into batter.
07 - Transfer batter to prepared loaf pan, smooth top. Bake 50-60 minutes until toothpick inserted in center comes out clean. Cover with foil after 35 minutes if browning too quickly.
08 - Let cake cool in pan for 15 minutes, then remove and transfer to wire rack to cool completely.
09 - Whisk powdered sugar and lemon juice until smooth. Drizzle over cooled loaf before serving.