6 oz. chocolate chips
1/2 c. sugar
3 1/4 c. graham cracker crumbs
5 tbsp. sugar
10 tbsp. melted butter
2 (8 oz.) pkg. cream cheese
3/4 c. sugar
1/2 c. sour cream
1 tsp. vanilla
4 eggs

Preheat oven to 325 degrees. Combine over hot water (or in microwave), chocolate chips, and 1/2 cup sugar, until melted. Set aside. In a small bowl, combine graham cracker crumbs, 5 tablespoons sugar and melted butter. Pat firmly into 10 inch springform pan, covering bottom and sides. In a large bowl, beat cream cheese until light and creamy. Gradually beat in 3/4 cup sugar. Mix in sour cream and vanilla. Add eggs, one at a time, beating well after each.

Divide batter in half. Stir melted chocolate into 1/2; pour into pans. Cover with plain batter. Swirl with a knife to marbelize. Bake at 325 degrees for about 70 minutes or until only 2-3 inch circle in center will shake. Cool at room temperature and refrigerate. I like to top it with sour cream topping from Buffalo Cheesecake recipe. In that case, use some of the graham cracker crumbs in the bottom of an 8 inch pan and bake some of the batter in it. The 8 inch pan does not need to bake as long, maybe only about 30 minutes.