Heat oven to 350 and prepare two 9-inch round baking pans.
In bowl of stand mixer fitted with whisk attachment, place the butter, sugar and lemon zest. Beat until light and fluffy.
In a separate bowl, mix together dry ingredients and set aside.
With the mixer on low speed, add the eggs, one at a time, combining thoroughly in between. With the mixer still running, add the lemon juice. (batter will look curdled, but its not)
Add one third of the dry ingredients and 1/2 cup of the buttermilk. Mix, then stop and scrape the sides of the bowl. Repeat, adding another third of the dry ingredients and the remaining 1/2 cup buttermilk. Mix, then stop and scrape. Add the remaining third of the dry ingredients and mix until completely combined and the batter is light and fluffy.
Divide the batter evenly between the prepared pans.
Bake for 25-30 minutes, or until an inserted toothpick comes out clean. Let the cakes cool before removing from the pans.