Sometimes, I like to add a teaspoon or two of vanilla extract to the cheesecake filling, but this is entirely optional.
Make sure you're using pumpkin purée, not pumpkin pie filling. Pumpkin pie filling is already sweetened and spiced, which will affect the flavor and texture of your cheesecake bites.
I don’t recommend using pre-ground graham cracker crumbs, as I’ve had readers report that their treats turn out too dry and crumbly when using store-bought crumbs. I believe this happens because pre-ground crumbs are usually much finer than the crumbs most people make when crushing graham crackers at home. The finer texture of the pre-ground crumbs results in more crumbs per cup than when you make them from scratch, leading to a drier mixture.
If you must use pre-ground graham cracker crumbs, I suggest starting with 1 cup (which is half the amount the recipe calls for). Since 16 full sheets of graham crackers typically yield about 2 cups of homemade crumbs, you can gradually add more pre-ground crumbs, ¼ cup at a time, if the dough feels too sticky to mix. Continue adding until the dough holds together well and can be easily rolled into balls.