Preheat your oven to 350 degrees Fahrenheit. Prepare three 9 inch cake pans by lining the bottom with parchment paper and greasing the sides of the pan with butter.
In a large bowl, sift the cake flour with baking powder, baking soda, salt, and sugar. Set aside. Do not skip this step.
3 cups cake flour, 2 teaspoons baking powder, 1 teaspoon baking soda, 1/2 teaspoon salt, 1 1/2 cups sugar
In a large bowl using a handheld mixer or in the bowl of a stand mixer, beat the egg. Then add in the oil and then the evaporated milk.
2 large eggs, 3/4 cup vegetable oil, 1 1/4 cup evaporated milk
Slowly add the flour mixture to the egg mixture and beat together on medium speed, for about 30 seconds.
Stir in the lime juice and zest so that the zest is evenly distributed throughout the batter.
1/3 cup key lime juice, 1 tablespoon lime zest
Evenly divide the batter between the three cake pans. Bake for 20 to 25 minutes or until the cake springs back when lightly touched in the center. Let the cakes cool in the pans for 2 minutes before removing them from the pans to a cooling rack to cool completely.