Marbled Sweet Potato Cheesecake

For crust, combine crushed crackers and chopped nuts. Stir in melted butter. Press mixture onto bottom and about 2-inches up the sides of a 10-inch springform pan; set aside. For filling beat cream cheese and sugar with electric mixer on medium speed until combined. Add sweet potatoes, cinnamon, vanilla, nutmeg, ginger, salt, and cloves. Beat well. Add eggs all at once. Beat on low speed just until combined. Remove 1/2 cup filling; stir in melted chocolate. Gently pour plain filling into springform pan. Drop small spoonfuls of chocolate mixture onto filling. Use a spatula to gently swirl batters Place pan in a shallow baking pan on oven rack. Bake in a 375°F (190°C) oven about 40 minutes or until center of cheesecake appears nearly set when shaken. Cool in pan on wire rack for 15 minutes. Use a small metal spatula to loosen from side of pan. Cool 30 minutes more. Remove side of pan. Cool completely. Chill in refrigerator for at least 6 hours.