1. Preheat the oven to 350°F and grease a standard loaf pan. Line it with parchment paper for easier removal if desired.

2. In a medium bowl, whisk together the flour, baking powder, and salt.

3. In a large bowl, beat the softened butter and granulated sugar until light and fluffy.

4. Add the eggs one at a time, mixing well after each addition. Stir in the lemon zest, lemon juice, and vanilla extract.

5. Add the dry ingredients in portions, alternating with the milk and sour cream. Mix gently until just combined.

6. Pour the batter into the prepared loaf pan and smooth the top.

7. Bake for 45 to 55 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs.

8. Let the loaf cool in the pan for 10 minutes, then transfer it to a wire rack.

9. Whisk the powdered sugar with the lemon juice until smooth. Drizzle over the cooled loaf.

10. Let the glaze set, then slice and serve.