Preheat oven to 350 degrees F. Butter a 9 by 13-inch pan, or 2 (6-inch) round pans.
In a large bowl, using an electric mixer, cream butter and sugar together, about 5 minutes. Beat in eggs, 1 at a time, then add the lemon zest.
In separate bowl, sift flour, baking powder, baking soda, and salt. In another bowl, combine lemon juice, buttermilk, and vanilla. Slowly add the flour mixture and wet ingredients, simultaneously, into the egg mixture and combine well. Divide batter between the prepared round pans, or sheet pan. Bake for 45 minutes to 1 hour, or when toothpick inserted into the center comes out clean. Remove from the oven and allow to cool in the pans. Slice, as desired, and serve.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.