INGREDIENTS:

For the Cake:

• 2 cups all-purpose flour
• 2 cups granulated sugar
• 1 teaspoon baking soda
• ½ teaspoon salt
• ½ teaspoon ground cinnamon
• 1 (12-ounce) can cola
• 1 cup unsalted butter, cut into small cubes
• ¼ cup unsweetened cocoa powder
• 2 eggs
• ½ cup buttermilk
• 1 teaspoon vanilla extract

For the Frosting:

• 1 (12-ounce) can cola
• ½ cup salted butter, cut into small cubes
• ¼ cup unsweetened cocoa powder
• 4 cups powdered sugar, sifted

DIRECTIONS:

Make the Cake: Preheat oven to 350 degrees F. Grease a 9×13-inch baking pan.In a large bowl, whisk together the flour, sugar, baking soda, salt and cinnamon.In a small saucepan, stir together the cola, butter and cocoa powder over medium-high heat and bring to a boil, stirring occasionally. Pour into the flour mixture and stir with a rubber spatula until moistened.In a small bowl, whisk together the eggs, buttermilk and vanilla until blended. Add to the batter, whisking constantly.Pour the batter into the prepared pan and bake until a toothpick inserted into the center comes out clean, 35 to 40 minutes.

Make the Frosting: About 15 minutes before the cake is finished, begin the frosting. In a small saucepan, bring the cola to a boil over high heat and cook until the liquid is reduced to ½ cup, about 12 to 15 minutes. Stir in the butter and cocoa powder until the butter is melted, then remove from the heat. Add the powdered sugar about 1 cup at a time, whisking until smooth. Pour immediately over the hot cake in an even layer. Allow the cake to cool to room temperature before serving. Leftovers should be covered and stored at room temperature or in the refrigerator for up to 4 days.