Preheat oven to 350 F (175 C).
In a medium bowl, stir together cookie crumbs, pecans and butter until evenly moistened. Press into the bottom of a 9” removable cheesecake pan. Bake for 15 minutes or until golden. Remove from oven and cool.
In a large bowl, beat together the Mascarpone and Ricotta with an electric mixer until light and fluffy ““ approximately 5 minutes. Add the pumpkin and beat well, then add the brown sugar, nutmeg, cinnamon and vanilla; continue beating until smooth. Add the eggs, one at a time, beating after each addition. Pour the filling into the cooled crust and bake for approximately 1 ½ hours or until a toothpick inserted in the centre comes out clean.
Remove from oven and allow to cool completely. Refrigerate until ready to serve. To serve, place cheesecake on a serving platter, remove the side ring and garnish
with whipped cream if desired.