Preheat the oven to 350 degrees F and line a 9x4 loaf pan with parchment paper. In a small bowl, whisk together flour, baking powder, and salt. Set aside.

In a large bowl, cream together butter, eggs, egg yolk, sugar, vanilla, and lemon extract.

Mix slowly until combined and then mix on medium-high speed for 5 minutes, or until light and fluffy.

Stir in flour mixture until combined.

Stir in buttermilk.

Pour batter into prepared loaf pan and bake 55 minutes, or until a toothpick inserted in the middle comes out clean.

Let cool in the pan 20-30 minutes and then remove to a cooling rack to cool completely.

In a small bowl mix together powdered sugar, milk, lemon juice, and lemon extract.

Pour the icing over the top of the lemon loaf.

Let icing harden for 30 minutes. Slice and enjoy!