01 - Preheat oven to 350°F. Grease and line a 9x5-inch loaf pan with parchment paper.
02 - In a medium bowl, whisk together flour, baking powder, baking soda, salt, and poppy seeds until well combined.
03 - In a large bowl, beat butter and sugar with an electric mixer until light and fluffy, about 2–3 minutes.
04 - Add eggs one at a time, mixing well after each addition. Mix in lemon zest, lemon juice, sour cream, milk, and vanilla until fully incorporated.
05 - Gradually fold in the dry ingredients until just combined; do not overmix.
06 - Toss raspberries with 1 tbsp flour to prevent sinking, then gently fold them into the batter.
07 - Spoon batter into prepared loaf pan and smooth the top. Bake for 50–60 minutes, or until a toothpick inserted in the center comes out clean. Tent loosely with foil after 35 minutes if browning too quickly.
08 - Cool in the pan for 15 minutes, then transfer to a wire rack to cool completely.
09 - Whisk powdered sugar and lemon juice until smooth. Drizzle over cooled loaf before serving.