Prepare the Crust

1. Mix Crust Ingredients: In a mixing bowl, combine graham cracker crumbs, melted butter, and sugar. Stir until the crumbs are evenly coated and resemble wet sand.
2. Divide the Mixture: Spoon the mixture evenly into the bottom of 6 clear cups, pressing down firmly to form a crust layer.

Prepare the Pumpkin Filling

1. Mix Filling Ingredients: In a separate bowl, whisk together the pumpkin puree, sweetened condensed milk, brown sugar, pumpkin pie spice, and vanilla extract until smooth and well combined.
2. Layer the Filling: Spoon the pumpkin filling over the crust layer in each cup, filling them about three-quarters full.

Chill and Serve

1. Chill: Place the cups in the refrigerator for at least 15 minutes to set slightly.
2. Add Toppings: Just before serving, top with a dollop of whipped cream and a sprinkle of pumpkin pie spice or cinnamon if desired.