To Make Base: Melt butter in a small saucepan. Stir in biscuit crumbs, 3 tablespoons dark brown soft sugar and 40g pecans. Press into ungreased 23cm springform tin.
To Make Filling: Beat cream cheese and 275g dark brown soft sugar together until smooth and fluffy. Slowly beat in eggs one at a time, just until blended. Stir in 1 teaspoon rum flavouring, 1 teaspoon vanilla, 4 tablespoons soured cream and 40g pecans. Pour filling into tiin.
Bake at 180 C / Gas 4 for about 55 to 60 minutes, until set. Remove tin to cake rack while you prepare topping.
To Make Topping: Stir together 350ml soured cream, 4 tablespoons dark brown soft sugar, maple flavouring and 1/2 teaspoon rum flavouring. Spread over cheesecake. Return to oven and bake for 10 minutes. Loosen sides of cake. Cool until almost room temperature, then chill for a few hours before serving.
If rum flavoured extract cannot be found, substitute in half the amount of dark rum. Maple flavoured extract can be purchased online.