Preheat oven to 350°. Combine first 3 ingredients. Press into a greased 9 x 13 pan. Bake 8 minutes; remove from oven. Beat cream cheese and sugar with an electric mixer until combined. Gradually beat in eggs, milk and vanilla. Reserve 1 cup mixture in a separate bowl, and combine with cheese ball mix. Pour plain cream cheese mixture over crust, spreading evenly. Drizzle orange mixture over the top; gently swirl with a knife or toothpick to create a marbled effect. Bake 30-35 minutes or until set. Cool slightly; cover and chill until served. Garnish with orange slices if desired. Makes 16 servings.