Preheat the oven to 350°. Position the rack in the lower third of the oven.
Wrap a 10-inch springform pan with a few layers of aluminum foil, making sure that the foil tightly covers the seam of the pan and reaches more than halfway up the sides of the pan. Spray the inside of the pan with nonstick cooking spray.
Grind the cookies in a food processor. Pour the cookie crumbs into the melted butter along with 1/4 cup sugar. Stir with a fork to combine. Press the mixture in the bottom and halfway up the sides of the springform pan. Bake 10 minutes. Transfer to a rack to cool and lower the oven temperature to 325°F.
Make sure ALL your ingredients are room temperature to avoid lumps!
Beat the cream cheese and remaining 1 1/2 cups sugar with an electric mixer. (I prefer using my stand mixer for this.) Beat in the eggs, pumpkin, vanilla, flour, pumpkin pie spice and salt and continue mixing until combined and very few lumps remain, about 2 minutes with a stand mixer.
Meanwhile, set 4 cups of water to boil in a kettle or on the stove or microwave (this is for the water bath).
Place the prepared crust into a large roasting pan (the kind you bake a turkey in). Pour the cheesecake onto the prepared crust. Transfer the roasting pan to the oven and fill with enough boiling water to reach about halfway up the springform pan.
Bake the cheesecake until the center is still slightly wobbly but the edges are firm to the touch, about 75 minutes. Turn off the oven and crack the oven door and let the cheesecake sit, undisturbed, for one hour.
Transfer the roasting pan with the cheesecake to a rack and let it cool for 45 minutes. Remove the springform pan, remove the foil, and let the cheesecake cool on the rack for about 3 hours. Run a knife around the edges to loosen and wrap with plastic wrap. Refrigerate overnight. When ready to serve, remove the springform pan sides and slide onto a serving platter.
Serve with whipped cream.
If substituting spices for the Pumpkin Pie Spice, use: 2 teaspoons ground cinnamon, 3/4 teaspoons each ground nutmeg and ground cloves and 1/2 teaspoon ground ginger.