FOR THE CAKE
- 8 ounces (2 sticks) unsalted butter, plus more for pan
- 2 1/4 cups all-purpose flour
- 3/4 cup unsweetened cocoa powder
- 1 teaspoon baking soda
- 1 teaspoon salt
- 1/2 cup milk
- 1/2 cup sour cream (4 ounces)
- 1 1/2 cups sugar
- 4 large eggs
- 1 teaspoon pure vanilla extract
FOR THE GLAZE
- 3 ounces bittersweet chocolate, chopped
- 1/2 cup heavy cream
- 2 tablespoons unsalted butter
- Make the cake: Preheat oven to 325 degrees. Butter a 14-cup Bundt pan. In a large bowl, whisk together flour, cocoa, baking soda, and salt. Mix milk and sour cream in a glass measuring cup.
- With an electric mixer on medium-high speed, beat butter and sugar until pale and fluffy, 3 to 5 minutes. Add eggs, 1 at a time, beating well after each addition; add vanilla. Reduce speed to low; add flour mixture in 2 batches, alternating with the milk mixture and beginning and ending with the flour; beat until just combined.
- Transfer batter to prepared pan; smooth top with an offset spatula. Bake until a cake tester comes out clean, about 55 minutes. Transfer pan to a wire rack to cool completely.
- Make the glaze: Place chocolate in a heatproof bowl. Bring cream to a simmer in a small saucepan; pour over chocolate. Let stand 2 minutes. Add butter, and mix until smooth. Let stand, stirring occasionally, until slightly thickened. Pour glaze over cake.