This sour cream mocha cake is a knockout. Made with unsweetened chocolate and instant espresso, it’s wicked dense, intense, chocolatey, and easy to toss together from ingredients you already have at home with an espresso frosting that’s as light as the cake is dense. A very “adult” dessert.
Perfect Frosting Every Time
Don’t even think about using a stand mixer, handheld mixer, whisk, or spoon to make the frosting. It needs to be a food processor. And make sure to keep it running for the required amount of time.
Crank the oven to 350°F (175°C) and adjust the oven rack to the middle position. Butter two 8-inch cake pans and line the bottoms with parchment paper. Butter and flour the paper, tapping out any excess flour.
Melt the chocolate, either in a microwave on medium or in a pot set over another pot filled with an inch of simmering water. (Make sure no water splashes into the chocolate or it’ll become grainy. And then you’ll become grouchy.) Remove from the heat to cool until just warm.
Meanwhile, dump the sugar, flour, baking soda, and salt in the bowl of a stand mixer fitted with a paddle attachment.
In a bowl, whisk together the hot espresso, sour cream, oil, butter, and vanilla and chocolate extracts. Pour the espresso mixture into the flour mixture in the stand mixer and mix on low until just blended, about 30 seconds.
Slowly drizzle in the beaten eggs and mix on medium until smooth. Scrape in the melted chocolate and beat until the batter is uniform in color, about 15 seconds. The batter will be thin but that’s how it should be.
Divide the batter evenly between the 2 pans and bake for 30 to 40 minutes, until a tester comes out clean. Transfer the cakes to a wire rack to cool for 10 minutes. Run a sharp knife around the edge of each cake and invert them onto another rack to cool completely.
Make the espresso frosting
Dissolve the espresso granules in the water.
Pour the espresso mixture into a food processor and add the butter, sugar, and heavy cream. Process until it becomes light and fluffy, about 5 minutes. The frosting will initially look curdled and destroyed. And then just when you’re about to lose all faith, everything will come together beautifully. Swear.
You simply must use a food processor for the frosting. Seriously. Or the frosting won’t come together.
Assemble the cake
Place 1 cake on a cake stand or serving plate. Frost the top and then stack the second cake on top. Frost the top and sides. Devour immediately.Originally published June 2, 1999.
If you’re sensitive to caffeine, you may get a subtle buzz from this cake. Rather than risk a sleepless night if you tend to eat a late dessert, simply make the recipe with decaffeinated espresso. The intense mocha flavor won’t be affected in the least.