Preheat oven to 350°F (180°C).
Grease an 8” springform pan and line the bottom with parchment.
In a large, microwave-safe bowl, add the chocolate and butter. Melt the chocolate and butter in the microwave, using 20 second intervals, stirring between each. Generally, 40 seconds total is sufficient.
Sift the cocoa powder, salt and spices into the melted chocolate mixture. Add the vanilla. Stir until mixture is smooth.
In another bowl, whisk the 4 egg yolks and 2 whole eggs with a ¼ cup of the sugar until pale and foamy.
Add the chocolate mixture to the egg yolk mixture and gently stir until combined.
Place the egg whites in the bowl of an electric mixer fitted with the whisk attachment and beat until foamy, then gradually add ½ cup of the sugar and beat until firm peaks (the whites are holding their shape, but not too stiff, the tip of the peak curls over itself when the beater is lifted).
Add a third of the egg whites to the chocolate mixture and stir until combined.
Gently fold in the rest of the egg whites. Pour the mixture into the prepared springform pan.
Bake for about 40 minutes, or until the cake is risen and cracked and the centre doesn’t jiggle.
Allow the cake to cool in the pan on a cooling rack for 1 hour. The cake will sink in the middle as it cools. Carefully release the sides of the pan and slide the cake onto a flat serving plate or cake stand.
To make the maple cream, add the whipping cream, maple syrup and vanilla to the bowl of an electric mixer fitted with the whisk attachment. Whip until the cream is firm but not stiff.
Top the cake with the cream; drop the cream onto the sunken part of the cake and gently spread it out towards the edges of the cake. Lightly dust with cinnamon.
Serve immediately. Serves 8 to 10.