Fill molds 1/3 full with plain yogurt, then place in the freezer. Freeze for 1-2 hours, or until yogurt is set.
In a small bowl or glass, mix together 1/2 cup yogurt with canned pumpkin. Stir until combined, then pour over frozen yogurt in ice cube molds, making sure to leave space at the top for third layer.
Return to freezer for another 1-2 hours, or until set.