In a large mixing bowl, mix the ground pecans and cookie crumbs; add the melted butter and mix well.
To form the crust, press the crumb mixture into the bottom of a 9-inch springform pan.
Refrigerate for at least 30 minutes.
In a mixer, beat the cream or Mascarpone cheese until smooth, then add the sugars and spices and beat until the mixture is light and fluffy, approximately 3-4 minutes.
Add the sweet potato purée and mix until just blended.
Add the eggs one at a time, scraping bowl after each egg.
Stir in heavy cream at low speed until completely blended.
Pour the filling into into the pan.
Put the pan into a 1 to 1/2 inch bain marie, or warm water bath (it's a good idea to wrap the bottom and sides of the springform pan to prevent water from leaking in.) Cook the cheesecake in the bain marie for 50 minutes at 350°F.
Cool the cheesecake at room temperature for 45 minutes.
Chill for at least 4 hours before serving.
While the cheesecake is cooling, make the praline sauce: melt the butter in a saucepan, then add the brown sugar, cream and pecans.
Bring to a boil over high heat, then reduce the heat and simmer for 5 minutes.
To serve, place each serving a slice of pie onto a dessert plate, then spoon a pool of warm praline sauce over and around each serving.
Top with a dollop of fresh whipped cream, and garnish with a sprig of mint.