Mix the butter, powdered sugar, cinnamon and salt with the dough hook of the mixer. Add the egg and keep stirring. Add flour, hazelnuts and cocoa powder and stir in until a smooth dough has formed. Wrap it in cling film and put it in the fridge for 1 hour.
Then put in a greased 28-inch tart pan and prebake for 18 minutes at 175 °; let cool down.
Filling:
Put the cream, maple syrup, cinnamon and chili powder (amount to taste!) In a saucepan and bring to the boil. Remove from heat and melt the chocolate and butter in it.
Put the mixture on the tart base and let it set in the refrigerator for at least 1 hour.