Preheat oven to 150 degrees C. In a large bowl mix together 1/4 cup melted butter, wafer crumbs and white sugar. Press firmly on the bottom of a 23cm springform pan.
In a large bowl beat cream cheese until fluffy. Gradually beat in sweetened condensed milk. Mix in eggs one at a time blending well after each. Stir in 1/4 cup rum, vanilla essence and nutmeg. Pour into the prepared pan.
Bake in preheated oven for 40 to 50 minutes or until set. Cool for about 5 minutes then run a knife blade carefully around the inside rim of the pan to loosen the cake from the sides. Cool in the pan to room temperature then refrigerate until completely chilled. Remove from pan before serving.
In a small bowl dissolve the cornflour in 1 cup of water. Melt 2 tablespoons butter in a medium saucepan. Stir in brown sugar and the cornflour mixture. Bring to a boil, stirring constantly. Reduce heat and simmer for 10 minutes. Remove from heat and add 2 tablespoons dark rum. Cool. Just before serving stir in pecans. Serve sauce with cheesecake.