Dark Chocolate Cake

I found this recipe in a magazine while waiting at the airport.  I tried it once as it was written and the cakes fell.  The second time I tried it the cake did not fall.  It is very important not to overmix this cake.  It is delicious!  You can also make marshmallows to top this cake with, but I didn't.  It is a very rich cake that is best eaten with a glass of milk.  Was a BIG hit when I made it.

Cake

6 oz. (3/4 cup) unsalted butter; more for the pans
13-1/2 oz. (3 cups) unbleached all-purpose flour; more for the pans
3/4 cup canola oil
4-1/2 oz. bittersweet chocolate, finely chopped
3 cups granulated sugar
2-1/4 oz. (3/4 cup) natural unsweetened cocoa powder
3 large eggs, at room temperature
3/4 cup buttermilk, at room temperature
2 Tbs. pure vanilla extract
2-1/2 tsp. baking soda
1/2 tsp. kosher salt

Frosting

2-1/2 cups heavy cream
3 oz. (6 Tbs.) unsalted butter
1 vanilla bean, split lengthwise and seeds scraped out
6 oz. bittersweet chocolate, finely chopped
2 cups granulated sugar
6 oz. (2 cups) natural unsweetened cocoa powder; more for decorating
1/2 cup Lyle’s Golden Syrup
1/4 tsp. kosher salt

To make the cake:
Position racks in the bottom and top thirds of the oven and heat the oven to 350°F. Butter three 9x2-inch round cake pans and line each with a parchment round. Butter the parchment, then dust with flour and knock out the excess.

In a 3-quart saucepan, combine the butter, oil, chopped chocolate, and 1 cup water. Heat over medium heat until melted.

In a large bowl, whisk the flour, sugar, baking soda, salt and cocoa powder. Pour the hot chocolate mixture into the sugar mixture and whisk until combined.

Whisk in the eggs, one at a time, then whisk in the buttermilk and vanilla. Divide the batter evenly among the prepared pans.

Set two pans on the top rack and the third on the lower rack. Stagger the pans on the oven racks so that no pan is directly over another. Bake, swapping and rotating the pans’ positions after 20 minutes, until a toothpick inserted in the center of each cake comes out clean, 35 to 40 minutes. Cool on racks for 10 minutes. Invert the cakes onto the racks, remove the parchment and cool completely.

To make the frosting:
In a 4-quart saucepan over low heat, combine the cream, butter, and vanilla bean and seeds and stir until the butter is melted. Remove the vanilla bean and whisk in the chopped chocolate until melted. Whisk in the sugar, cocoa powder, syrup, and salt until smooth—be sure the cocoa powder dissolves completely. Pour into a 9x13-inch pan and freeze until firm, about 1 hour.