In a blender, add the water and the Joi cashew base and blend on high for 1-2 minutes, or until the mixture is completely blended. This should give you about 2 cups of creamy cashew milk to use in the custard.
In a medium saucepan, whisk together the sugar, cornstarch, cinnamon, salt, and ginger until combined. Slowly whisk in the cashew milk until combined, and then whisk in the vanilla extract and pumpkin puree.
Cook this mixture over medium heat while whisking constantly for about 8 minutes, or until the mixture becomes very thick. Remove from the heat and whisk in the vegan butter until melted. Pour into a bowl and cover the custard with plastic wrap. Chill for at least 2 hours, or until fully cooled before assembling.
While the custard cools, make your gingersnaps and make sure you have 6 clean jars to assemble your parfaits in.
When you're ready to assemble, start by breaking up a gingersnap cookie into pieces and putting at the bottom of a jar. Layer with your cooled pumpkin custard and coconut whipped cream. Repeat with another set of layers, and then cover and chill for at least 1 hour. Enjoy!