• Preheat the oven to 350 and grease an 8-inch round cake pan and place a cut-out round parchment paper in the bottom.

To make the cake

• In the bowl of a stand mixer combine all the dry ingredients and mix together.
• In a separate bowl, whisk together the oil, eggs, buttermilk and vanilla. Slowly whisk in the hot water, making sure to keep whisking as you pour (otherwise you’ll have scrambled eggs.
• With the stand mixer on low speed, add the wet ingredients to the dry ingredients, mixing just to combine.
• Pour the batter into the prepared baking pan and bake in the middle rack of the oven and bake for 30-35 minutes.
• Cake is done when a toothpick inserted into the center comes out clean. Let cool in pan for five minutes and remove from pan to a cooling rack to cool completely.

To make the frosting

• To make the frosting, bring cream, syrup, and salt to a simmer in a large saucepan over medium-high heat. Remove from heat and stir in milk chocolate, sour cream, nutella and butter. Let sit, stirring occasionally, until chocolate and butter are melted and mixture is smooth and no streaks of white remain. Transfer to a medium bowl. Let frosting sit at room temperature, stirring every once in a while. The frosting will look gross at first, but don't freak out - it will thicken and become shiny and spreadable in like an hour or so. Keep stirring until smooth. It should be the consistency of sour cream; if not, chill another 5 minutes and stir.
• Chill the Ferrero rocher candies for about 15 minutes in the freezer, along with the knife you’ll be chopping them with. Chop them up.
• Spread the frosting on the cooled cake, and sprinkle the chopped Ferrero rocher candies on top.