1. Butter and sugar are whisked together in a mixer, then eggs are added one at a time
2. Grate the pumpkin and add to the batter
3. Mix the flour and spices together in a bowl, then sift into the cake batter and stir to combine
4. Pour the cake batter into a greased springform pan with parchment paper at the bottom
5. Bake the cake in a convection oven at 175 degrees Celsius (347 degrees Fahrenheit) for about 35-40 minutes
6. Let the cake cool completely before slicing it in half and spreading the apricot jam on the bottom layer
7. Assemble the cake, then make the cream cheese frosting
8. Whisk cream cheese, powdered sugar, and vanilla sugar until light and fluffy, then spread on top of the cake
9. Finally, garnish the cake with orange zest and crushed hazelnuts