Preheat oven to 350 degrees. Spray donut pan with nonstick cooking spray.

Drain the liquid from the can of yams/sweet potatoes. Puree in a blender or food processor or mash them as best you can with a fork or potato masher.

In a medium bowl, beat together the pureed sweet potatoes, egg, maple syrup, greek yogurt, and vanilla extract until well combined.

In a small bowl, combine the flour, baking soda, salt, and cinnamon.

Stir the dry ingredients into the wet ingredients until just combined.

Spoon the batter into the donut pan and bake for 11 minutes.

Let cool for 5 minutes before removing from the pan.

While the donuts are cooling, prepare the glaze.

In a small saucepan over low heat, melt the butter and maple syrup together. Whisk to combine. Whisk in the powdered sugar until smooth.

Dip the tops of the donuts into the glaze or spoon it on. The glaze hardens quickly so you may need to reheat it to keep it at the right consistency. There is just enough glaze to coat the tops of the donuts and you may need to use a spoon to spread it on the tops of the last few donuts as there won't be enough in the pan for dipping.