Level: Easy
Yield: 6 to 8 servings
Nutritional Analysis Per Serving
Serving Size: 1 of 8 servings
Calories: 822
Total Fat: 48 g
Saturated Fat: 24 g
Carbohydrates: 94 g
Dietary Fiber: 2 g
Sugar: 68 g
Protein: 9 g
Cholesterol: 176 mg
Sodium: 434 mg
Total: 2 hr 45 min (includes cooling time)
Active: 35 min

Ingredients

Nonstick baking spray, for the pan
15 tablespoons unsalted butter, at room temperature
2 cups sugar
1/2 cup buttermilk
1/3 cup vegetable oil
3 teaspoons vanilla extract
4 large eggs, at room temperature
2 cups all-purpose flour (see Cook's Note)
1 teaspoon baking powder
1 teaspoon kosher salt
1/2 teaspoon baking soda
1 1/2 teaspoons ground cinnamon
6 ounces semisweet chocolate, finely chopped
2 tablespoons light corn syrup
3/4 cup heavy cream

Special equipment:
a nonstick 9 by 5-inch loaf pan

Instructions

Position a rack in the middle of the oven and preheat to 375 degrees F. Spray a 9-by-5-inch nonstick loaf pan with baking spray and set aside.
In a stand mixer fitted with the paddle attachment, beat 12 tablespoons of the butter with 1 1/2 cups of the sugar on medium-high speed until light and fluffy, about 6 minutes.
Meanwhile, whisk together the buttermilk, vegetable oil, vanilla, and eggs in a liquid measuring cup. In a medium bowl, whisk together the flour, baking powder, salt, and baking soda; set aside.
With the mixer on medium-low speed, add one-third of the flour mixture and mix just until combined, about 20 seconds. Add half of the egg mixture and mix until just combined. Repeat with the remaining flour and egg mixtures, scraping down the sides and bottom of the bowl with a rubber spatula between additions.
Transfer the batter to the prepared pan and smooth the top with a spatula or offset spatula. Firmly tap the pan on the countertop about 10 to 15 times to release any large air bubbles.
Bake on the center oven rack, rotating the pan halfway through, until the top is deep golden brown and a cake tester inserted in the middle comes out clean, 55 minutes to 1 hour. Let cool in the pan for 15 to 20 minutes, then invert onto a wire rack and cool completely, about 1 hour.
Meanwhile, mix the cinnamon with the remaining 1/2 cup sugar in a small bowl. Spread two-thirds of it in a rectangle roughly the size of the loaf on a baking sheet.
When the cake is completely cool, place the chocolate and corn syrup in a medium heatproof bowl. Heat the cream in a small saucepan over medium heat to a simmer, then pour it over the chocolate. Let stand 1 minute, then stir with a spatula until smooth, fully melted, and glossy.
Melt the remaining 3 tablespoons butter in a small microwavable bowl in the microwave. Brush the top and all four sides of the cake generously with the melted butter. Gently press each side into the cinnamon-sugar mixture, using your hands to adhere any bare spots. Sprinkle the remaining cinnamon sugar over the top. Pour the chocolate mixture over the top of the cake, then transfer to a serving platter.

Cook's Note: When measuring flour, we spoon it into a dry measuring cup and level off the excess. (Scooping directly from the bag compacts the flour, resulting in dry baked goods.)