CRUST: Lightly greast an 8 or 9 inch springform man. Combine all crust ingrediants mix well and press evenly over bottom and up a little on the sides of pan. Bake at 350 for 10 minutes, remove and let cool while making the rest of the cheesecake.
CHEESECAKE: In your mixer beat ricotta cheese at high speed gradually adding sugar and then eggs. Reduce speed to low and add cocoa, flour and vanilla until blended. Add sour cream, blend at low speed until smooth, stir in hazelnuts. Pour mixture into crust. Bake at 350 until cake sets about 1 hour 15 minutes or until set. Remove from oven and cool completely. Chill for at least 8 hours. Garnish with chocolate swirls.