Preheat oven to 350 degrees F.
In medium bowl, combine crumbs, sugar and cinnamon. Add melted butter. Press down flat into a 9-inch springform pan. Set aside.
Beat cream cheese until smooth. Add pumpkin puree, eggs, egg yolk, sour cream, sugar and the spices. Add flour and vanilla. Beat together until well combined.
Pour the batter into the foiled-wrapped springform pan. Tap the pan against the counter a few times to release any air bubbles in the batter.
Prepare the water bath
Place the pan in a larger roasting pan. Pour boiling water into the roasting pan until the water is about halfway up the sides of the cheesecake pan. Make sure that the water won't seep through your foil, you will end up with a soggy crust. Sometimes I will elevate my springform pan by placing a roasting grate underneath it so it's just barely above the water. Use your imagination.
Bake the cheesecake
Bake at 350°F for 1 hour or until the top looks slightly dry. If the middle is slightly wobbly, that’s fine. Err on the side of underbaking rather than overbaking.
Turn off the oven heat and open the oven door open just by 1-inch. Let the cheesecake cool inside the oven for 1 hour. Don't skip this part. This will prevent cracks from forming.
Remove the cheesecake from the oven and from the water bath, unwrap the foil, and transfer it to a cooling rack. Run a thin-bladed flexible knife around the edge of the cake to make sure it's not sticking to the sides (which can cause cracks as it cools). Let the cheesecake cool completely to room temperature on the rack.
Refrigerate until completely chilled, at least 5 hours or up to 3 days. Store the cheesecake uncovered to avoid creating condensation, which will create a mushy texture.