To prepare the cherry topping, place 2 cups cherries in a blender or food processor, and process until smooth. Combine the pureed cherries, 1/4 cup sugar, lemon juice, and cornstarch in a small saucepan. Bring to a boil, and cook 1 minute, stirring constantly. Pour cherry topping into a bowl; cover and chill.
Preheat oven to 350°.
To prepare the crust, combine crumbs, 1/4 cup sugar, butter, and egg white in a bowl; toss with a fork until well-blended. Press crumb mixture into the bottom of a 10-inch springform pan coated with cooking spray. Bake at 350° for 10 minutes; cool on a wire rack. Reduce oven temperature to 300°.
To prepare the filling, combine sour cream, milk, and cheeses in a large bowl. Beat at medium speed of a mixer until well-blended. Add 1 1/4 cups sugar, cocoa, vanilla, and eggs; beat well. Stir in minichips. Pour cheese mixture into prepared pan. Bake at 300° for 50 minutes or until almost set (center will not be firm, but will set up as it chills). Turn oven off; cool cheesecake in closed oven 40 minutes. Remove from oven; cool on a wire rack. Spread cherry topping over cheesecake. Top with cherry halves. Cover and chill 8 hours.
