Stir the graham cracker crumbs and melted butter together in a bowl until the crumbs are evenly coated. Press the mixture firmly into the bottom of an 8x4 inch loaf pan to form a crust layer.
Beat the cream cheese, pumpkin puree, sugar, vanilla extract, and pumpkin pie spice in a mixing bowl until the mixture is smooth and no lumps remain.
Fold the whipped topping into the pumpkin mixture gently until it is fully combined and the color is uniform.
Spread the filling evenly over the crust in the pan. Smooth the top with a spatula.
Place the pan in the refrigerator and chill for at least two hours until the bars are firm. Cut into four pieces and top each with two candy pumpkins before serving.