Preheat oven to 350 degrees. Coat an 8- or 9-inch loaf pan with cooking spray. If desired, line the bottom and two sides with parchment paper and spray the paper with cooking spray (this helps remove the bread from the pan).

To make the loaf, in a medium bowl, combine the flour, baking powder, baking soda, and salt. Set aside.

In the bowl of an electric mixer, beat together the butter and sugar until creamy. Beat in the eggs, one at a time. Scrape down the sides of the bowl. Beat in the sour cream, lemon juice, lemon zest, and vanilla until blended. Beat in the flour mixture until just blended; do not over-mix.

Transfer the batter to the prepared pan and smooth the surface. Bake for 40 to 45 minutes, until a wooden pick comes out clean or with little moist bits clinging to it.

Cool completely in the pan, on a wire rack, before glazing.

To make the glaze, in a medium bowl, whisk together the powdered sugar, lemon juice, and 1 tablespoon of the milk. Whisk until you reach a thick glaze, adding more milk if necessary. Spoon half of the glaze over the cake and cool until set. Repeat, using the remaining glaze.