Preheat Your Oven: Begin by preheating your oven to 350°F (175°C). Grease your loaf pan and line it with parchment paper, allowing an overhang on two sides for easy removal.
Mix Dry Ingredients: In a mixing bowl, whisk together the all-purpose flour, granulated sugar, cocoa powder, baking powder, baking soda, and salt until they are well combined.
Add Wet Ingredients: In another bowl, using an electric mixer, beat the eggs until they're creamy. Then add in the buttermilk, vegetable oil, and vanilla extract. Mix until well combined.
Combine Wet and Dry Mixtures: Gradually pour the wet ingredients into the dry mixture. Mix until you have a smooth batter. Don't overmix.
Add Hot Water: Now, pour in the hot water and mix until it's fully incorporated into the batter. The batter will be thin, but that's perfectly normal.
Bake: Pour the batter into your prepared loaf pan and place it in the preheated oven. Bake for approximately 55-60 minutes or until a toothpick inserted into the center comes out clean.
Cool and Serve: Once the cake is done, let it cool in the pan for 10 minutes, then transfer it to a cooling rack to cool completely. Once cooled, slice and serve.