The trick to this whipped cream frosting is powdered sugar. It keeps the whipped cream stable for much longer than usual. This cake sat out at a warm room temperature for over 3 hours and did not become runny.
I've prepared this "wowzers" of a cake for Christmas Day dessert. Since the fridge is usually (gratefully) packed with food and has no storage for this behemoth, I set it on the porch or in the garage (when the temperature is in the low 50s to upper 30s).
One more thing: the original recipe makes an incredibly large cake (three 9" layers). I halved the cake recipe and used two 8" cake pans. But I kept the original amounts for the whipped cream frosting and the ganache. You might end up with a little extra whipped cream. But I'm sure you can find a good use for it somewhere else (like directly in your mouth).
Please read through the recipe first. It's absolutely not a difficult cake to make---but timing is very important: the cake needs to cool completely so it won't liquify the whipped cream when it's frosted. Then the frosted cake need to be refrigerated for an hour before adding the chocolate glaze in order for the whipped cream frosting to stabilize. And the chocolate glaze can't be too hot (it will melt the frosting) or too cool (it won't pour). And then the frosted and glazed cake needs to be refrigerated again in order to "set" the glaze. High maintenance? Yes. Difficult? No! You can do this!
Here's the printable recipe.
Here's the printable recipe.
(Makes two 8" layers)
1/2 cup (1 stick) unsalted butter
1 cup water
1/2 cup canola oil
2 cups sugar
1/2 cup unsweetened cocoa powder
2 cups all-purpose flour
2 large eggs
1/2 cup buttermilk
1.5 teaspoons baking soda
1/4 teaspoon salt
1.5 teaspoons vanilla extract
Whipped Cream Frosting
4 cups chilled heavy whipping cream
1 and 1 /4 cups powdered sugar
Chocolate Ganache Glaze
4 ounces bittersweet chocolate, chopped
1/2 cup heavy cream
1/4 cup corn syrup (I used dark...light would work, too)
2 teaspoons vanilla
Preheat oven to 350 degrees. Arrange baking rack in center of oven. Line the bottom of two 8" cake pans with parchment paper. Generously butter paper and sides of pan. Dust with flour, tapping pan to remove excess flour if necessary.
In a medium saucepan set over medium heat, mix together the butter, water, and canola oil. In a large mixing bowl, whisk together the sugar, cocoa powder and flour until very well combined.
Pour in the butter/oil mixture and continue whisking until very smooth. Whisk in the eggs, one at a time, and then the buttermilk. Whisk in the baking soda, salt and vanilla all at once--just until combined.
Bake for 25-35 minutes or until the cake edges begin to pull away from the sides of the pan AND a toothpick inserted into the center of the cake comes out clean. (I give such a wide range of baking times because I have experienced both times with my ancient, unpredictable oven. It would be a crying shame to over (or under) bake this cake. Please monitor and check the cakes often as they bake.)
Remove the cakes from the oven when done. Cool on a wire rack (in the cake pan) for 15-20 minutes (this is an important step and will make all the difference in getting the cake out in one piece). Invert the cakes on the baking rack and they should emerge whole. Remove parchment paper and continue cooling for at least 2 hours.
To make the frosting: whip the chilled heavy cream with either 1) a whisk attachment on a mixer (at high speed), or 2) by hand with a wire whisk until soft peaks form. (Don't overwhip or you'll end up with butter.) After the peaks have formed, add the powdered sugar and whip until combined.
Once the cake is completely cooled and you're ready to frost it: place one cake on a platter, rounded side down. Add a generous layer of frosting to the top and smooth with an off-set spatula. Top with the second cake, rounded side up. Generously frost the sides and top. Refrigerate for at least an hour so the whipped cream will stabilize.
To make the chocolate ganache glaze: When you're ready to pour the glaze over the chilled, frosted cake: place the chopped chocolate in a medium bowl. Heat the cream in a small saucepan JUST until it's steaming (don't let it boil or it will get a "skin" on it which is gross and a bit difficult to smoothly incorporate into the chocolate). Pour the steamed cream over the chocolate and begin to whisk until thick and smooth. Add in the corn syrup and the vanilla. Whisk well. Pour the glaze into a measuring cup or a pitcher (something with a little pour spout works best...). Let the glaze cool for about 5-10 minutes. Don't let the glaze sit much longer than that or it will begin to harden and will become difficult to pour. (If you feel that it is not "pourable" enough, add a bit more corn syrup or warm it up a little.) Cover the top of the cake completely with the glaze, smoothing it with an off-set spatula if necessary. Encourage the glaze to drizzle over and down onto the sides of the cake.
Allow the glaze to set (refrigerated is best for about 1 hour).
To slice, use a long serrated knife. Dip the knife in hot water between each slice to keep slices as pretty as possible.
The refrigerated cake keeps for about 2 days before the whipped cream frosting begins to separate.
Recipe slightly adapted from: The Pastry Queen: Royally Good Recipes from the Texas Hill Country's Rather Sweet Bakery and Cafe