Preheat your oven to 350 degrees F (175 degrees C). Grease a bundt cake pan with butter.
Prepare the crust. In a bowl, mix together the graham cracker crumbs and icing sugar. Melt the butter or margarine in the microwave and stir it into the dry ingredients until evenly blended. Press this mixture firmly onto the bottom and up the sides of the prepared pan.
Prepare the cheesecake filling. In a large bowl, cream together the cream cheese, sugar, and salt until light and fluffy. Beat in eggs one at a time, then stir in sour cream, flour, vanilla extract, ginger powder, ground cinnamon and nutmeg. Fold in mashed sweet potatoes.
Pour the cheesecake filling over the crust. Place this in a preheated oven and bake for 30 minutes or until the center is set and slightly golden brown. Let cool for 10-15 minutes before transferring to a serving plate.
Prepare the candied pecans. In a skillet, heat sugar over medium heat until it melts and becomes a thick syrup. Add the pecans and stir to coat them completely. Continue cooking for about 3 minutes, stirring constantly, until all the sugar has melted and is evenly coating the nuts. Remove from heat and spread out on parchment paper or waxed paper to cool before serving.