Preheat the oven to 350°F (175°C). Grease and flour a 9×5-inch loaf pan, or line it with parchment paper.
In a large bowl, cream the softened butter and granulated sugar together using an electric mixer on medium speed until light and fluffy, about 3 to 5 minutes.
Add the eggs one at a time, beating well after each addition to fully incorporate.
In a separate bowl, whisk together the all-purpose flour, baking powder, and salt.
Gradually add the dry ingredients to the butter mixture in three additions, alternating with the milk in two additions, beginning and ending with the dry ingredients. Mix on low speed just until combined after each addition.
Fold in the fresh lemon zest and lemon juice gently with a spatula until evenly distributed.
Pour the batter into the prepared loaf pan and smooth the top with a spatula.
Bake in the preheated oven for 55 to 65 minutes, or until a toothpick inserted into the center of the cake comes out clean.
Remove the cake from the oven and let it cool in the pan for 15 minutes.
Run a knife around the edges of the pan to loosen the cake, then invert it onto a wire rack to cool completely before slicing and serving.