Start by getting your oven warmed up to 350°F (175°C). Lightly grease a 9×5-inch loaf pan, and then line it with parchment paper so you’ll be able to lift the cake out easily once it’s done.

In a medium bowl, take the cocoa powder and pour the boiling water over it. Whisk until it turns smooth and glossy, and then let it rest for a minute so the chocolate flavor can deepen.

In another bowl, whisk together the buttermilk, eggs, oil, and vanilla until everything looks smooth. Add the cocoa mixture to this bowl and stir until you have a deep, dark chocolate mixture.

Now grab a large bowl and combine the flour, sugar, espresso powder, baking soda, baking powder, and salt. Mix well so all the dry ingredients are evenly blended.

Pour the wet mixture into the dry ingredients and gently fold everything together. Stop as soon as the dry streaks disappear over mixing will make the loaf tough, so go easy here.

Once the batter is ready, pour it into your prepared loaf pan and smooth the top. Slide it into the oven and bake for about 55 to 65 minutes. You’re looking for a skewer or knife to come out mostly clean, with just a few moist crumbs.

Let the loaf cool in the pan for about 10 minutes, then lift it out using the parchment and let it finish cooling completely on a rack.