Preheat oven to 450° degrees. First, place the softened sour cream and 2 teaspoons vanilla in large mixer bowl. If you have a blender, beat on medium speed until smooth or you can go with the old and reliable spoon. Next you need to add flour, about 1 tablespoon at a time to blend well. Add eggs and beat well. Next take a small bowl and combine the cocoa powder and 1/4 cup sugar. Add the oil, 1/2 teaspoon vanilla and 1-1/2 cups of the cream cheese mixture and mix until well blended. Alternately spoon plain and chocolate mixtures into prepared crust, ending with dollops of the chocolate on top. Be sure to gently swirl with knife or spatula for a marbled effect.
Bake at 450° degrees for 10 minutes. Without opening the oven door, lower temperature to 250° degrees and continue cooking for 30 minutes more. Without opening the oven door, turn off heat and let cheesecake sit in oven for 30 minutes.
Remove from oven and loosen sides with knife. Let cool and chill. Serve your Chocolate Marble Cheesecake Recipe.