Coat bottom of a 10-inch springform pan with cooking spray. Wrap outside bottom and sides of pan with heavy-duty aluminum foil; set aside. Position knife blade in food processor bowl; add the ricotta cheese and cream cheese, and process until smooth. Add brown sugar and next 6 ingredients; process until smooth. Pour into a large bowl; stir in pumpkin, and set aside. Beat 4 egg whites (at room temperature) and cream of tartar at high speed of an electric mixer until foamy. Gradually add 1/4 cup sugar, 1 tablespoon at a time, beating until stiff peaks form. Gently stir one-fourth of egg white mixture into pumpkin mixture. Gently fold in remaining egg white mixture. Pour into prepared pan; place in a large, shallow pan. Add hot water to larger pan to a depth of 1 inch. Bake at 300° for 50 minutes. Remove from oven; let cool in water bath 1 hour. Remove springform pan from water; remove foil from pan. Cover and chill at least 8 hours. Place 3 tablespoons sugar in a small saucepan over medium-high heat. Caramelize by stirring often until sugar melts and is golden (about 5 minutes). Rapidly spread mixture onto a baking sheet coated with cooking spray. Cool completely. Break mixture into small pieces. Position knife blade in processor bowl; add crystallized sugar. Pulse 6 times. Sprinkle over cheesecake. Yield: 12 servings (serving size: 1 wedge). Nutritional Value: Calories 233 (20% from fat), protein 0.4g, Fat 7.5g (Sat 4.2g, Mono 0.3g, Poly 0.4g), Carb 33.7g, Fiber 0.7g, Chol 50mg, iron 1.5mg, sodium 264mg, calcium 117 g PC 114