Nutella Mousse Crunch Cake

 About a month ago I saw a link floating around facebook titled "What crazy national holiday falls on your birthday?"

"Hey, I don't know!" I thought, and so I clicked on the link.  Turns out, my birthday is also known as...Disaster Day.  Uh, yikes.  I mean, I'm sure I was as whiny and obnoxious as the next baby, but calling my birth a disaster seems a little harsh, man.

Of course, I did a little digging and discovered that "Disaster Day" is actually a day to prepare for disasters.  You know, make sure your house is prepared for an earthquake or flood, stock up on first aid and go over fire safety.  Well, that seems a little better.  Plus, during my digging I discovered that my birthday also falls on an even better holiday.

World Nutella Day.  Now, that's more like it.

I've discussed the tastiness of Nutella before.  But this was better, because now that I knew that World Nutella Day fell on my birthday, of course I had to make my birthday cake with it.

Nigella Laweson has a pretty well known Nutella Cake recipe.  And while it looked good, I wanted something a little more special for my birthday.  When I came across a pretty chocolate mousse cake with a crunchy hazelnut bottom, I knew I had to give it a try.

Nutella Mousse Crunch Cake (very loosely adapted from Bon Apetit)

Cake
3/4 cup plus 2 tablespoons flour
1/4 cup plus 2 tablespoons cocoa
1 cup sugar
3/4 teaspoon baking powder
3/4 teaspoon baking soda
3/4 teaspoon salt
1/2 cup milk
1 egg
1 teaspoon vanilla
1/4 cup melted butter
1/2 cup boiling water

Crunch
5 oz. milk chocolate or hazelnut milk chocolate
1/3 cup chopped toasted hazelnuts
1 cup crispy rice ceral

Mousse
1 1/2 cups heavy whipping cream
1 teaspoon vanilla
1 cup Nutella

Toppings (optional)
1/4 cup Nutella
whole hazelnuts

Special Equipment:
Mixer with a whisk attachment
8" or 9" springform pan

To make the Cake (can be made a day ahead):

Preheat oven to 350°F.  Grease the bottom of a 9" cake pan and cut out a circle of parchment paper to put in the bottom (I've started doing this every time I bake a cake just to ensure it doesn't stick when I flip it out of the pan).  Butter and flour the bottom and sides of the pan (or use baker's spray).  Set aside.

Combine all the dry ingredients (flour, cocoa, sugar, baking powder, baking soda, salt) in the bowl of your mixer.  With the speed on medium, add the milk, egg, vanilla and butter and mix until well-blended.  Add the boiling water last and mix until incorporated.  The batter will be very thin.

Pour into your prepared cake pan and bake for 30-35 minutes, until a toothpick inserted in the center of the cake comes out dry.  Allow to cool for 10 minutes before removing from the pan onto a cooling rack.  If you are using an 8" springform pan (as I was), use the bottom as a guide to trim the excess off the 9" cake layer.

To make the Crunch:

While the cake is cooling, if you haven't already, you can toast your chopped hazelnuts in the oven.  Place in a rimmed baking sheet and bake until aromatic, about 5 minutes.  Set aside.

Chop up the chocolate and place in a metal mixing bowl over a pot of simmering water (do not let the bottom of the bowl touch the water) or double boiler.  Stir until completely melted, then mix in the crispy rice cereal and chopped hazelnuts until well-coated.

Transfer the chocolate mixture to the springform pan and press into the bottom using a large spoon or your fingers (might get a little messy).  Place the cake layer on top and press down so it adheres to the melted chocolate.

To make the Mousse:

Put the heavy cream in the bowl of a mixer with a whisk attachment.  Whisk until stiff peaks form.  Heat Nutella in a microwave for 30 seconds and stir.  Add Nutella and vanilla to the whipped cream and mix by hand until uniform in color.

Add the mousse to the top of the cake and use a spatula to smooth it out.  Refrigerate for at least 4 hours or overnight.

To decorate, heat 1/4 cup Nutella in the microwave for 20 seconds and drizzle over the top of the set cake, then place whole hazelnuts on top in your favorite design.  Get ready for the "ooohs" and "aaaahs".