Preheat oven to 350° Fahrenheit. Line 3 5- or 6-inch cake pans with parchment paper and spray with nonstick cooking spray; set aside.
Mix cake mix, egg whites, milk and oil together in a large bowl, mixing until combined.
Divide the batter between the prepared pans and bake 27-32 minutes until a toothpick inserted in the center comes out clean. Remove from the oven and let cool 10 minutes, then remove cakes from pans to a cooling rack to cool completely.
Make the buttercream:
In a medium saucepan, whisk together sugar and flour until well blended.
Place saucepan on stove over medium heat and, while whisking, add in milk. Whisk until no lumps remain.
Continue to whisk until mixture comes to a low boil and thickens enough to coat the back of a spoon. Remove from heat and cool for 45 minutes-1 hour.
In a stand mixer fitted with a whisk attachment, or with a hand mixer, beat butter for 3-5 minutes until pale and creamy.
Pour in cooled milk mixture 1/4 cup at a time, mixing well between additions, until light and creamy. Don’t stress if it looks a bit curdled – just give it a few more minutes and it will come together. When it’s almost ready, add peppermint and vanilla and whip until incorporated.
Make the ganache:
Microwave chocolate in microwave safe bowl for 1 minute to soften. Bring heavy whipping cream just to a simmer then pour over chocolate. Make sure the chocolate is fully covered . Let set for 5 minutes .
Whisk gently to combine cream and chocolate, do not incorporate air.
Allow the ganache to cool slightly before decorating the cake. Make sure your cake is very cold so ganache sets quickly.
Assemble the cake:
Use freshly made ganache for drips (make sure your cake is very cold so ganache sets quickly)
Frost the first cake layer with the white frosting.
Top with the second layer of cake, then repeat by frosting this layer.
Place the third cake layer on top.
Spread a thin crumb coat layer of buttercream over the entire cake, smoothing it out as best as possible.
Freeze the cake for 30 minutes before applying a second layer of buttercream to cover the cake.
Make sure the cake is cool from freezing and that the ganache has cooled. Drizzle the ganache onto the center of the cake and push it towards the edges of the cake so it drips down.
Decorate the top of the cake by placing chocolate shards in the center.
Sprinkle with powdered sugar or coconut, then decorate the top with Ferrero Rafaello candy.
Store at room temperature.
The calories shown are based on the cake being cut into 12 pieces, with 1 serving being 1 slice of cake. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate. **We are not dietitians and recommend you seek a nutritionist for exact nutritional information.**