For the cake:
- 2C all-purpose flour
- 2 1/2C granulated sugar
- 3/4C unsweetened cocoa powder
- 2t baking soda
- 1t salt
- 1C grapeseed oil
- 1C sour cream
- 1 ½ C water
- 2T distilled white vinegar
- 1t vanilla extract
- 2 large eggs
- 1C toasted, chopped hazelnuts (If raw, toast them at 350 degrees for 10-15min.)
- Pinch of fleur de sel (optional)
For the Nutella frosting:
- 10oz mascarpone cheese
- 4oz unsalted butter, cubed, at room temperature
- 4 ½ – 5C powdered sugar
- 1C Nutella
- 1/6C heavy cream
Make the cake:
- Preheat the oven to 350 degrees. Now, prep your pans. Parchment the bottom and coat them evenly in oil spray.
- In a large bowl, whisk together the flour, sugar, baking soda, cocoa powder, and salt. Add the oil and sour cream, stirring to combine.
- Gradually stream in the water, whisking between additions. Add the vinegar and vanilla extract. Whisk in eggs.
- Evenly divide the batter between your three pans and bake for 30-35 minutes, or until a tester comes out clean and when gently pressed in the center, springs back. Let cakes cool for 10 minutes, then remove from pans and continue to cool on a wire rack for about 30 minutes before you even think about frosting the cake. In fact, I recommend wrapping the cakes in plastic wrap and popping them in the refrigerator for about an hour. These cakes are very soft and very tender, so if you decide to frost it, when it is still warm, you’re going to have a bad time.
Make the frosting:
- In the bowl of a stand mixer, fitted with a paddle attachment, beat together the mascarpone and butter until light and fluffy on medium-high speed. (Heads up, this won’t get quite as fluffy as cream cheese frostings because mascarpone doesn’t have the same body.)
- With the mixer on low, slowly add in the powdered sugar, 1C at a time, stopping at 4 ½ C. Scrape down the bowl after each addition.
- Add the Nutella. This product is oily and surprisingly sticky, so make sure you are scraping down the bowl often to ensure everything is incorporated. Remember that ½ C of powdered sugar we left out? If your frosting looks a little too soft, add it in, if not, leave it out.
- Switch out the paddle attachment with the whisk attachment. With the mixer turned up to medium speed, stream in the heavy cream and beat until fully incorporated.
- ASSEMBLE: Cut off the tops of your cakes to makes sure they are even. Spread a healthy layer of frosting over a layer, sprinkle chopped hazelnuts, and top it with another layer of cake. Repeat twice. Sprinkle a pinch of fleur de sel on the top.
- To match the picture: Add a chocolate ganache for drizzle. Mine is made up of just semisweet chocolate chips and heavy cream, but there are TONS of recipes out there that have more interesting ingredients to match your tastes.