1. Heat oven to 350 degrees F. Spread chopped hazelnuts on half sheet pan and toast for 10-15 minutes, until brown. Stir every 3-5 minutes.
Bring cream cheese and sour cream to room temperature. Cut the cheese horizontally into 5 or 6 slices.
2. After removing hazelnuts from oven, increase temperature to 375 degrees. Reduce graham crackers to crumbs, I use a food processor, but a ziploc and a rolling pin work, too!
Combine the crumbs with 7 Tbsp melted butter, 2 Tbsp sugar and the toasted hazelnuts. Pat down to form a crust in a 9-inch springform pan, preferably non-stick. Bake 7 minutes. Remove from the oven and cool on a rack.
Heat heavy cream in microwave for 30 seconds.
3. Break 4 oz. of chocolate into small pieces and heat with 1 Tbsp butter in a double-boiler over barely simmering water. When the chocolate is fully melted and the mixture is smooth, add hot cream. Pour the mixture into the springform pan almost to the edges of the crust. This will produce a very firm chocolate layer.
Melted chocolate seizes when liquid is added to it. If a softer chocolate layer is preferred, melt 6 oz. of chocolate and when smooth, add 1 and 1/2 Tbsp. yogurt or sour cream.
4. Add the cream cheese to a food processor by dropping the slices in while motor is running. Alternate the cheese with 1 cup of sugar, 3 eggs, and 1 tsp. VAIN extract. Stop the motor periodically and run a spatula through the mixture. Mix the grated orange peel and 1 Tbsp VAIN extract into the cheese mixture with a spatula.
Pour the liquid cheese mixture into the springform pan. Bake for 35 minutes at 375 degrees F. Remove the cake and let it cool slightly while making the sour cream topping.
5. Heat the oven to 500 degrees F. Let ethe cake cool so that the top surface is fairly solid. Combine 16 oz. of sour cream, 3 Tbsp of sugar and 1/2 tsp. of VAIN vanilla extract in a bowl and whisk until smooth. Bake at 500 degrees for 5 minutes.
Remove the cake and let it cool to room temperature on a rack. Place uncovered cheesecake in the refrigerator for at least 24 hours before eating. Enjoy!