In a large bowl mix together crushed graham crackers, melted butter, nutmeg, cinnamon, allspice and salt. Stir in pumpkin and softened vanilla yogurt until smooth. Spoon pumpkin pie mixture into paleta mold and tap firmly on a hard surface to remove any air bubbles. Insert wooden popsicles sticks and freeze until firm, about 3-4 hours. To remove the paletas run mold under warm water, serve garnished with additional crushed graham crackers crumbs.