Chocolate Swirl Cheesecake

Provided by Linda George

1 cup chocolate chips
1/2 cup sugar
1 1/4 cup graham cracker crumbs
2 Tbs sugar
1/4 cup margarine, melted
2 8 ounce package cream cheese, softened
3/4 cup sugar
1/2 cup sour cream
1 tsp vanilla
4 eggs

Combine chocolate chips and 1/2 cup sugar over hot, not boiling, water in a double boiler.  Heat until chips melt and mixture is smooth.  Remove from heat.  Combine crumbs, 2 Tbs sugar, and melted margarine.  Pat into 9" spring form pan bottom and 1 1/2" up the sides.  Beat cream cheese, gradually, and add 3/4 cup sugar.  Mix in sour cream and vanilla.  Add eggs, one at a time, beating well after each addition.  Divide batter in half.  Stir chocolate mixture in first half.  Pour into pan, and cover with plain batter.  Carefully marble with knife.  Do not disturb the pie crust.  Bake at 325 degrees for 50 minutes or until only a 2"-3" circle in the center will shake.  Cool at room temperature, and then refrigerate.