Preheat the oven to 350 degrees F. Grease the bottom and sides of an 8 - 9.5" springform pan with butter. Use the springform pan to trace and cut a circle of parchment paper then place the parchment paper circle on the bottom of the greased pan. Set aside.

In a medium bowl, whisk together the spelt flour, finely ground hazelnuts, breadcrumbs and baking powder. Set aside. In the bowl of a stand mixer with the whisk attachment or in a large bowl with a hand held beater, beat the egg whites on high until stiff. Gently empty the egg whites into a large bowl and set aside. Clean and dry the stand mixer bowl and whisk attachment, then beat the egg yolks and sugar together on high until light and creamy, approximately 1 minute. Add the flour mixture to the egg yolk mixture, switch to the paddle attachment and mix on low until combined. Add the egg whites and fold gently with a large spatula until just combined.

Pour the mixture into the springform pan and spread evenly. Bake for 30 - 35 minutes or until a toothpick inserted in the centre comes out clean. Remove the cake from the oven and let cool completely before cutting into 3 layers.

In a small bowl, pour the gelatine over the cool water. Add the boiling water and stir constantly until completely dissolved. Set aside. In another small bowl, mix the cocoa powder, instant coffee and sugar with 2 tbsp of room temperature water and stir until the instant coffee has dissolved. Set aside.

In the bowl of a stand mixer with whisk attachment or in a large bowl with hand held beater, beat the whipping cream until soft peaks. Then with the mixer running, add the gelatine in a steady stream and beat the whipping cream until stiff. Add the cocoa powder mixture and beat on medium until combined. Transfer approximately 1 cup of the filling to a pastry bag with a decorating tip.

Place the bottom layer of cake on a cake plate or stand. Spread half the jam on top and 1/3 of the remaining filling. Place the second layer on top, spread the remaining jam on it, sprinkle with rum (optional) and spread another 1/3 of the remaining filling evenly on top. Top with the last layer of cake.

Fill the cracks on the sides of the cake with cream, then frost the sides and top of the cake with the rest of the cream.

Shave the chocolate with a large knife or potato peeler. Sprinkle chocolate around the base of the cake then lift and gently press the shavings onto the sides of the cake with a spatula. Pipe 12 florets on the top of the cake around the edges and top each floret with a hazelnut.

Chill and refrigerate for a minimum of 8 hours up to 24 hours before serving to let all the flavors mingle.