Take 1 cup of the cake mix out of the box and set it aside for later.
Mix the remaining cake mix with 1/2 cup (1 stick) melted vegan butter, then press it evenly into an oiled baking dish to form the bottom cake layer.
Add the pumpkin, coconut milk, brown sugar, chickpea flour, pie spice, vanilla, and salt to a blender and blend for about 30 seconds until all ingredients are well combined.
Pour the pumpkin mixture over the first layer and spread it out evenly.
Mix the reserved cake mix with 1/4 cup sugar and 4 tablespoons butter, then crumble it evenly over the pumpkin pie layer.
Bake at 350°F (176°C) for 55 minutes.
Allow it to cool completely before cutting and serving.
Notes
Allow it to cool completely before cutting.
Store in the fridge uncovered until thoroughly cooled. Don't cover until all the steam has left the pumpkin pie cake.
Store leftover pumpkin pie cake in the refrigerator after 24 hours.