Preparation Steps

• Heat the oven to 330°F (165°C). Generously butter and flour a 10–12 cup Bundt pan (or use baking spray with flour). Set a wire rack over a sheet of parchment for glazing later.
• Bloom the cocoa: Warm 1/2 cup (120 ml) of the milk until steaming. Whisk in the cocoa powder and instant coffee (if using) until smooth and glossy. Let cool until just warm, about 5 minutes.
• In a bowl, whisk together the flour, baking powder, and salt; set aside. In a separate small bowl, whisk the eggs with the vanilla until evenly combined.
• Beat the butter in a stand mixer on medium speed for 1 minute to aerate. Gradually add the sugar and continue beating until very light and fluffy, 3 to 4 minutes, scraping the bowl once or twice.
• With the mixer on low, stream in the egg-vanilla mixture in 3 additions, mixing just until incorporated after each and scraping down the bowl as needed.
• Add half of the dry ingredients and mix on low just until no floury streaks remain. Beat in the cocoa-milk paste. Add the remaining dry ingredients, then the remaining 5/6 cup (195 ml) milk, mixing on low only until the batter is smooth. Give the batter a final fold by hand to ensure everything is evenly combined.
• Scrape the batter into the prepared pan and tap firmly on the counter 2–3 times to release large air bubbles. Let the filled pan stand for 5 minutes before baking to slightly relax the batter.
• Bake on the center rack for 60 to 70 minutes, or until a skewer inserted near the center comes out with a few moist crumbs or an instant-read thermometer reads about 200°F (93°C). If the top darkens too quickly, tent loosely with foil for the last 15 minutes.
• Cool in the pan on a rack for 20 minutes, then loosen the edges with a thin spatula and invert onto the rack. Cool completely, 1 to 2 hours, before glazing.
• Make the ganache: Heat the cream in a small saucepan over medium until just beginning to simmer. Pour over the chopped chocolate and add the butter. Let stand 2 minutes, then whisk from the center outward until smooth. Allow to sit 15–20 minutes until thickened to a slow-pour consistency.
• Finish: Set the cake on the rack over parchment. Spoon or pour half the ganache over the top and let it drip. Chill for 10 minutes to set slightly, then add the remaining ganache for a luscious second coat. Rest until the glaze is set before slicing.