Cream the butter, sugar and maple syrup until light and fluffy.
Gradually beat in the eggs.
Sift in the flour, spice and baking powder then fold in along with the oats, apple and nuts.
Spread evenly in the cake tin.
Make the topping by melting the butter then stirring in the other ingredients, then scatter over the cake.
Bake for 40 minutes in the middle of the oven then reduce the heat to 150C/130 Fan/300F/Gas 2 and bake for a further 10 to 15 minutes.
Cool in the tin.
While the cake is cooling make the caramelised nut topping by toasting the whole pecans in a dry pan. Stir continuously and do not overcook.
Add the butter, sugar and maple syrup and stir until bubbling and the mixture is starting to thicken.
Turn off the heat, stir in 1 tablespoon of water and then carefully lift out the pecans and lay on top of the cake in a pattern, then coat with the caramel from the pan. Leave to cool and set.