In a mixing bowl, combine the pumpkin puree, crushed graham crackers, powdered sugar, pumpkin pie spice, and vanilla extract. Mix until well combined and a dough forms.
Using a small cookie scoop or spoon, portion out the mixture and roll it into balls about 1 inch in diameter. Place them on a baking sheet lined with parchment paper.
Refrigerate the truffles for about 30 minutes to firm up.
Melt the white chocolate in a microwave-safe bowl in 30-second intervals, stirring in between until smooth.
Dip each chilled truffle into the melted white chocolate, ensuring it is fully coated. Use a fork to lift it out, allowing any excess chocolate to drip off.
Place the coated truffles back on the parchment paper and immediately sprinkle with finely chopped nuts or sprinkles if desired.
Allow the truffles to set at room temperature or refrigerate until the chocolate has hardened.