Preheat the oven to 350F. Coat a 9x13” cake pan with cooking spray then line it with parchment paper.
Add the butter and granulated sugar to the bowl of an electric stand mixer fitted with the paddle attachment. Beat on medium speed for a 3-4 minutes or until smooth and creamy.
Add the eggs one by one, beating to combine after each addition. Add the lemon zest and beat until combined.
Sift the flour, baking powder, baking soda and salt together in a separate bowl.
Add the lemon juice, buttermilk and vanilla to another bowl, and stir to combine.
Add 1/3 of the dry ingredients to the butter and sugar mixture in the mixer. Mix until just combined, then add 1/2 of the wet ingredients. Mix again, and repeat the process with 1/3 of the dry ingredients, and the other 1/2 of the wet ingredients. Add the final 1/3 of the dry ingredients, and mix just until you have a smooth batter.
Transfer the batter to your prepared cake pan and bake for 30-35 minutes, or until a skewer poked into the center of the cake comes out clean.
Leave the cake in the pan for about 15 minutes before releasing the cake from the pan onto a wire rack to cool completely.