Preheat oven to 350 degrees F. Grease and flour up to 10 (9 inch) cake pans.
In the bowl of a stand mixer fitted with a paddle attachment or a large bowl, beat together the butter and sugar until smooth and light. Beat in the eggs, one at a time.
In a medium bowl, combine the flour, baking powder, and salt. Mix into the butter mixture, one cup at a time, just until incorporated. Gently mix in the evaporated milk, water, and vanilla extract.
Place a scant 2/3 cup of the prepared batter into each greased cake pan. Use a small spatula or the back of a spoon to evenly smooth the batter. Place the pans on the center rack of the preheated oven and cook until the cake springs back when lightly touched and is no longer sizzling, 8-10 minutes. Allow to cool in the pan for 5 minutes before transferring to wire rack to cool completely. Repeat with remaining batter, re-greasing the pans between use. Allow to cool completely before layering with frosting.