Preheat the oven to 375 F and line the base of an 8-inch springform cake tin with baking paper.
In a clean bowl, mix the cookie or graham cracker crumbs with 2 tablespoons of light brown sugar and the melted butter.
Pour the mixture into the prepared cake tin and with the back of a measuring cup or spoon, press the moist graham cracker crumbs until they are compact and flat against the base of the cake tin.
Place the cake tin in the fridge for 10 minutes to allow the base to harden.
Meanwhile, in a clean bowl or stand mixer add the cream cheese and beat it for 1 minute to soften.
Add the remaining ⅓ cup of light brown sugar and beat it together with the cream cheese for 2 to 3 minutes, until everything is fully combined.
Add the pumpkin puree, eggs, vanilla extract, cinnamon, mixed spice, and flour to the bowl and mix again until everything is combined.
Finally, add ¼ cup of heavy cream and beat everything together for another 30 seconds.
Remove the cake pan from the fridge and pour the pumpkin cheesecake batter on top of the hardened biscuit base.
Tap the cake tin lightly on the countertop a few times to allow any trapped air bubbles to rise to the surface.
Carefully wrap the outside of the cake tin with a few layers of aluminum foil, then place the cheesecake in the center of the oven on a large baking tray with sides.
Pour enough water into the base of the baking tray so that it is roughly 1 inch deep, then bake the cheesecake for 1 hour. The cheesecake is ready when the sides are fairly set but the middle of the cake wobbles slightly.
After 1 hour, turn the oven off and open the door to allow the cheesecake to cool completely. Once it has reached room temperature, transfer the cheesecake to the fridge for 6 to 8 hours, or overnight.
When the cheesecake has had time to chill through, gently remove it from the cake tin and set it on a plate.
Whip up the remaining ½ cup of heavy cream and use it to decorate the top of the cheesecake.