To make the cake, pre-heat the oven to 180°c and line 3x 20cm cake tins with baking paper.
Beat the butter and sugar together until light and creamy.
Add the eggs one at a time and beat well after each addition.
Beat in the vanilla and the sweet potato puree.
In a separate bowl, combine the flour, baking powder, baking soda and spices and mix well.
Add the flour mixture and milk, alternatively, to the butter and sugar mixture. Mix well after each addition and scrape down the bowl.
Transfer the batter to the prepared cake tins.
Place in the oven and bake for 20-25 minutes or until the cakes are golden brown and a skewer inserted comes out clean. (Remember, all ovens differ so your cake might bake longer or in less time than mine.)
When the cakes are cooked, remove from the oven and allow to cool completely on wire racks.
To make the buttercream, beat the butter and icing sugar until light and fluffy then add the maple syrup and beat for another 2 minutes. Set aside.
To make the maple-candied nuts, simply combine the ingredients in a non-stick frying pan and place over medium heat. Allow the maple syrup to caramelise for 5 minutes then tip out onto a baking-paper lined plate. Allow to cool completely.
For the Chantilly cream, whip the cream until soft peaks form then add the sugar and the vanilla seeds and whip until cream has formed stiff peaks.
To assemble the cake, layer the cakes with Chantilly cream and cover in the maple buttercream.