Preheat oven to 325°F (160°C). Wrap the bottom of a 9-inch springform pan with heavy-duty aluminum foil.
Combine graham cracker crumbs, melted butter, and granulated sugar in a bowl. Press into the bottom of the springform pan.
In a large bowl, beat cream cheese and granulated sugar until smooth. Add sweet potato puree, eggs, sour cream, vanilla extract, cinnamon, nutmeg, ginger, and salt. Mix until just combined.
Pour batter over the crust. Place springform pan in a larger roasting pan. Add hot water to the roasting pan, coming halfway up the sides of the springform pan (water bath).
Bake for 70-75 minutes, or until the edges are set but the center still has a slight jiggle. Turn off the oven and let the cheesecake cool completely in the oven with the door ajar.
Chill the cheesecake for at least 6 hours, or preferably overnight.
For the praline topping, melt butter in a saucepan over medium heat. Add brown sugar and cook, stirring constantly, until sugar is dissolved. Stir in heavy cream, vanilla extract, and salt. Bring to a simmer and cook for 2-3 minutes, or until slightly thickened.
Remove from heat and stir in pecan halves. Pour praline topping over the chilled cheesecake just before serving.