Preheat oven to 350 degrees. Goop two 8 x 2 pans (recipe for goop in the link below). Soak 2 baking strips in cold water.
In a medium bowl sift or whisk all purpose flour, cake flour, baking powder, baking soda, salt, and lemon zest.
In a medium bowl, combine buttermilk, eggs, zest and Lemon Flavor paste.
In the bowl of a stand mixer fitted with a paddle attachment, cream butter and sugar until light and fluffy.
Add flour and milk mixtures alternating in 3 batches of flour, 2 batches of milk, beginning and ending with flour. Beat until just combined.
Divide batter evenly between pans; smooth tops. Bake until cakes just barely pull away from sides of pans, 30-40 minutes. Let cool in pans 10 minutes. Turn cakes out onto a metal cooling rack. If you used goop, your cakes should just slide out of then pan without hesitation.
Click here to get my GOOP recipe. This will change how you prepare your cake pans. You already have these ingredients in your cupboard - no need to buy sprays ever again!
If you want to make your own buttermilk substitute like I do (I never buy it), add 1 tablespoon of fresh lemon juice, lime juice, or distilled white vinegar to a 1 cup measure and fill the rest with reduced fat milk. Mix and let it sit for 5 minutes. Buttermilk!