Preheat your oven to 325°F (163°C).

Grease and flour your loaf pan.

In a mixing bowl, cream together the softened butter and sugar until light and fluffy.

Add the eggs one at a time, beating well after each addition.

In a separate bowl, whisk together the flour, baking powder, and salt.

In another bowl, whisk together the buttermilk, lemon zest, lemon juice, and vanilla extract.

Gradually add the dry ingredients to the butter mixture, alternating with the buttermilk mixture.

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

Bake for 60 minutes or until a toothpick comes out clean.

Let the cake cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.