• Preheat oven to 325 degrees Fahrenheit.
• Adjust the top rack to be positioned in the middle of the oven.

Cheesecake crust:

• Finely chop the nuts or add them to a food processor to chop up.
• Add all the ingredients to a large bowl and stir until well combined.
• Press the mixture into a 10-1/2 inch buttered springform pan.
• Using a measuring cup, press the crust and try to line the sides about to the middle of the pan edges, set aside.
• Refrigerate for at least 20 minutes.

Cheesecake Filling:

• Make sure all the ingredients are at room temperature before your begin.
• In the bowl of a stand mixer or in a large bowl using a hand mixer, beat the cream cheese until light and fluffy on medium-low speed.
• Add the sugar a little at a time and continue beating until well combined and creamy.
• Add the eggs one at a time and beat after each addition until well combined.
• Mix cornstarch with flour and add to the batter, whisk until fully combined. Careful not to over-mix.
• Add vanilla extract.
• Add the sour cream and beat well, stopping to scrape the sides and bottom of the bowl.
• Pour cheesecake batter into the prepared springform pan.
• Bake in the preheated oven for one hour and 15 minutes <-- NO!  Mine needed to bake for 2 hours, so check on yours while it bakes!
• Try not to open the door to the oven. At the 60 minute mark check on the cheesecake if its done. A small area in the center should wobble slightly and the edges should be puffed and light golden brown.
• Cover the top with aluminum foil so the top and edges don't burn.
• Mine was not baked enough and needed another full hour to bake and then it was PERFECT.  
• After the 2 hours are over, turn oven off and prop open oven door and leave the cheesecake to cool in oven for one hour.
• Time to chill: After one hour, remove from oven and place on a cooling rack for about 2 hours, until the cheesecake is cool enough to be transferred to the refrigerator.
• In a medium bowl, whisk together on medium-low speed sour cream and sugar until creamy and fully combined. Taste and add more sugar if needed.
• Spread the topping over the cool cheesecake using an offset spatula.
• Transfer to the refrigerator and chill for overnight or for 24 hours.