01 - Preheat oven to 350°F. Grease a 9x5-inch loaf pan and line with parchment paper for easy removal.
02 - In a medium bowl, whisk together flour, baking powder, baking soda, salt, and poppy seeds until evenly distributed.
03 - Using an electric mixer on medium-high speed, beat softened butter and granulated sugar until light and fluffy, approximately 2-3 minutes.
04 - Add eggs one at a time, mixing thoroughly after each addition. Beat in lemon zest, lemon juice, sour cream, milk, and vanilla extract until fully incorporated.
05 - Gradually fold the dry mixture into the wet ingredients using a rubber spatula. Mix only until just combined to avoid developing gluten.
06 - Toss fresh or frozen raspberries with 1 tablespoon flour to coat evenly, which prevents them from sinking during baking.
07 - Gently fold the flour-coated raspberries into the batter, taking care not to crush them.
08 - Spoon batter into the prepared loaf pan and smooth the top surface with a spatula for even baking.
09 - Bake for 50-60 minutes until a wooden toothpick inserted into the center emerges clean. If the top browns too quickly, tent loosely with aluminum foil after 35 minutes.
10 - Allow the loaf to rest in the pan for 15 minutes before transferring to a wire rack. Cool completely before glazing.
11 - Whisk powdered sugar with fresh lemon juice until smooth and pourable. Adjust consistency with additional juice if needed.
12 - Drizzle the glaze over the completely cooled loaf. Let set for 10 minutes before slicing into 8 servings.