Preheat oven to 325°F. Line an 8x8-inch pan with parchment.
Mix Graham crumbs, sugar (if using), and melted butter. Press into the pan and bake for 8 minutes. Cool slightly.
In a mixing bowl, beat cream cheese and sugar until smooth. Add pumpkin, spice, vanilla, and egg. Mix until creamy and well combined.
Pour cheesecake filling over the crust and smooth the top.
In a small bowl, mix crumble ingredients with a fork until crumbly. Sprinkle evenly over the pumpkin layer.
Bake for 30–35 minutes, or until the center is just set.
Cool completely, then refrigerate for at least 2 hours before slicing.
Top with whipped cream or caramel drizzle just before serving if desired.