Preheat your oven to 350°F (175°C). Lightly grease a 9×5-inch loaf pan and line it with parchment paper for easy removal.

In a medium bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.

In a large bowl, cream the softened butter and granulated sugar together until pale and fluffy (about 2 minutes).

Beat in the eggs one at a time, scraping down the bowl as needed.

Stir in lemon zest, lemon juice, vanilla, and sour cream until combined.

Gradually add the dry ingredients to the wet, mixing until just combined (don’t overmix!).

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

Bake for 48–55 minutes, or until a toothpick inserted in the center comes out clean or with a few moist crumbs.

Let the cake cool in the pan for 15 minutes, then lift it out and transfer to a wire rack to cool completely.

In a small bowl, whisk together powdered sugar and enough lemon juice to create a thick but pourable glaze.

Drizzle generously over the cooled cake.