Place a lightly greased 9-in. springform pan on a double thickness of heavy-duty foil (about 18 in. square). Securely wrap foil around pan. Sprinkle crumbs over bottom and sides of the pan; set aside.
In a large bowl, beat cream cheese and sugar until smooth. Add eggs; beat on low speed just until combined. Stir in orange juice and zest. Set aside 3/4 cup; pour remaining filling into pan.
Stir chocolate into reserved filling. Drop by spoonfuls over filling; cut through batter with a knife to swirl the chocolate.
Place springform pan in a large baking pan; add 1 in. of hot water to larger pan. Bake at 350° for 75-80 minutes or until center is just set and top appears dull.
Remove springform pan from water bath. Cool on a wire rack for 10 minutes. Carefully run a knife around edge of pan to loosen; cool 1 hour longer. Refrigerate overnight. Serve with whipped cream if desired.