Preheat oven to 350 F. Combine crumbs, nuts, 1/4 cup granulated sugar and butter; press into bottom and sides of 9-inch springform pan. Bake 5 minutes.
Combine cream cheese, brown sugar, pumpkin, cinnamon and salt, mixing at medium speed on electric mixer until well-blended. Add eggs, one at a time, mixing well after each addition. Blend in maple flavoring and 1 teaspoon vanilla.
Pour over crust. Bake 1 hour and 20 minutes.
Combine sour cream, 1/4 cup granulated sugar and 1/2 teaspoon vanilla. Carefully spread over cheesecake. Bake 5 minutes.
Loosen cake from rim of pan, cool.
Remove rim of pan. Chill several hours or overnight. Garnish with pecan halves, if desired.