Preheat the oven: Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans or line them with parchment paper.

1. Mix dry ingredients: In a large bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.
2. Add wet ingredients: Add the eggs, vegetable oil, buttermilk, and vanilla extract to the dry ingredients. Mix until smooth, using an electric mixer on medium speed or by hand with a whisk.
3. Add boiling water: Gradually pour in the boiling water, mixing until the batter is smooth. The batter will be thin, but this is what helps the cake stay moist.
4. Pour into pans: Divide the batter evenly between the two prepared cake pans. Tap the pans gently on the counter to release any air bubbles.
5. Bake the cake: Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean or with just a few moist crumbs.
6. Cool the cakes: Allow the cakes to cool in the pans for 10 minutes before transferring them to a wire rack to cool completely.
7. Frost and serve: Once the cakes have cooled, frost with your favorite frosting. Chocolate buttercream, whipped cream, or cream cheese frosting are great options!