Preheat oven to 400F. Spray 9-inch springform pan with nonstick cooking spray. Add graham cracker crumbs; shake to coat pan evenly. Set aside.
Combine pumpkin and ricotta cheese in food processor or blender; process until smooth. Add sugar, flour, milk powder, cinnamon, allspice, egg white, evaporated skim milk, oil, and vanilla; process until smooth.
Pour mixture into prepared pan. Bake 15 minutes. Reduce oven temperature to 275F; bake 1 hour and 15 minutes. Turn off oven; leave cheesecake in oven with door closed for 1 hour. Remove from oven; cool completely on wire rack. Remove sprinform pan side. Cover cheesecake with plastic wrap; refrigerate at least 4 hours or up to 2 days. Garnish with fresh fruit, if desired.