In a small bowl, mix 1/4 c of the non-dairy milk with the cornstarch until it forms a slurry. Set aside.
Place the mashed bananas, non-dairy milk, vegan butter, maple syrup, and turmeric in a small saucepan over medium heat, and bring to a simmer. Add in the cornstarch slurry, and whisk until smooth. Cook until the mixture is simmering and thickened, about 2-3 minutes.
Remove pan from heat and mix in the vanilla.
Transfer the pudding to a heat-proof container and refrigerate for a few hours, until completely cool (I cooled mine overnight).
Once cooled, fold in the whipped topping until the pudding is light and fluffy.
To build your banana pudding parfaits, layer the crushed graham crackers, banana, pudding, and whipped topping in small cups or ramekins, repeating until all ingredients are used.
Enjoy immediately, or cover with plastic wrap and refrigerate to enjoy the next day.