Preheat the oven to 350°F. Spray three 8-inch cake pans with baking nonstick spray. Line the bottom of the cake pans with 8-inch parchment paper circles and spray again.
In a mixing bowl, sift the flour. Add in the baking powder, baking soda and salt. Set aside.
3 ½ cups All-purpose flour, 2 teaspoon Baking powder, 1 teaspoon Salt, 1 teaspoon Baking soda
Using a mixer, beat the butter, oil, and sugar on high for 3 minutes. It will be almost white in color and creamy. Add in lemon zest, lemon juice, and sour cream. Beat on medium until combined. Scrape the bowl.
¾ cup Unsalted butter, ¼ cup Oil, 1 ½ cups White granulated sugar, 3 Large lemons zested, ¼ cup Lemon juice, ¼ cup Sour cream
Add in eggs one a time. Beat on high for 2 minutes. It will appear slightly separated, but this is normal.
4 Large eggs
Add in ⅓ of the dry ingredients and half of the buttermilk mix on low. Add in another ⅓ of the dry ingredients and the rest of the buttermilk. Finish with the rest of the dry ingredients. Mix until just combined.
1 cup Buttermilk
Pour the batter into the three cake pans. Bake for 18-22 minutes. Bake until a toothpick inserted comes out clean.
Let the cakes sit in the hot pans for 10 minutes. Then, transfer to a cooling rack. Cool completely.