01 -
Lower the oven rack to the lower-third position and preheat the oven to 350°F (177°C). Grease an 8×4-inch loaf pan with nonstick spray, or use a 9×5-inch pan for a shorter loaf.
02 -
Whisk the flour, baking powder, and salt together in a large bowl. Set aside.
03 -
Using a handheld or stand mixer fitted with a paddle or whisk attachment, beat the butter on high speed in a large bowl until smooth and creamy (about 1 minute). Add the granulated sugar and beat on high speed for 2 minutes until creamed, scraping down the bowl as needed.
04 -
With the mixer running on low speed, add the eggs one at a time. Stop the mixer, then add the sour cream, lemon juice, lemon zest, and vanilla extract. Beat on medium speed until combined, scraping down the sides as needed. The mixture might look curdled at this stage.
05 -
With the mixer on low speed, slowly add the dry ingredients until just combined. Use a whisk to eliminate lumps if necessary. Avoid over-mixing.
06 -
Spread the batter evenly in the prepared loaf pan. Bake for 55-65 minutes for an 8×4-inch pan or 45-60 minutes for a 9×5-inch pan, tenting with aluminum foil halfway to prevent over-browning. The cake is done when a toothpick inserted in the center comes out mostly clean.
07 -
Remove the cake from the oven and cool in the pan on a wire rack for 1 hour. Carefully remove the cake and allow it to fully cool on the rack before adding icing.
08 -
Whisk the icing ingredients together in a bowl, then pour over the cake. Serve immediately or let the cake cool completely for neater slices.