Preheat oven to 350 degrees. Prepare three 9-inch round cake pans by greasing and dusting with cocoa powder.
Whisk together flour, cocoa, baking soda, baking powder, salt, and sugar.
In a large mixing bowl, beat the eggs, buttermilk, water, fractionated coconut oil, and vanilla at medium speed until smooth, about 3 minutes. Slowly add dry ingredients just until combined. Do not overmix.
Divide the batter evenly between the three cake pans. Tap gently against the counter to remove the air bubbles.
Bake for 30 to 35 minutes or until a toothpick inserted in the center returns clean. Cool the cakes in pans for 10 minutes. Remove from pans and cool completely on wire racks.
To make the frosting, whisk together the sugar, cocoa, and salt. Beat butter at medium speed until light and fluffy, about 5 minutes. Reduce speed to low and slowly add the sugar mixture. As the mixture thickens, slowly add the milk to make the frosting smooth and fluffy.
The frosting will thicken when refrigerated and dry to form a crust when left at room temperature.
Let it set and enjoy it!