Preheat the oven to 325 degrees F. Prepare three 8-inch round cake pans by spraying the bottom and sides with nonstick spray, lining the bottom with parchment paper, and spraying the parchment paper. Set aside.
In a bowl of electric mixer, stir together all of the dry ingredients.
Combine eggs, buttermilk, water, oil and vanilla in a measuring cup and lightly beat with a fork.
With the mixer on low, add wet ingredients to the dry ingredients. Mix on low until the dry ingredients are incorporated, about 30 to 60 seconds. The batter will be thin. Scrape sides and mix on low for another 30 seconds. Divide batter evenly among prepared pans, about 15 to 16 ounces in each 8-inch pan.
Bake for 23 to 27 minutes (you may need more time depending on your oven), until toothpick comes out with just a few moist crumbs on it. Cool on wire racks for 10-15 minutes, then gently invert onto racks until cooled completely.
When cakes are completely cooled, I like to wrap each cake layer individually with plastic wrap and stick it in the refrigerator or freezer until I’m ready to frost. The cake will be easier to work with if it’s cooled a bit. If I’m making the cake a day or two before I actually need to frost it, I put it in the freezer to ensure freshness. If I’m frosting same-day, I still put the cakes in the freezer for an hour or so.