Preheat oven to 350°F. Grate apples, or you can very small dice them. Leave the skin on or peel, up to you!
In a medium bowl, whisk together milk, egg, sugar, vanilla, butter and yogurt.
In a separate bowl, combine baking powder, flour, sea salt, baking soda and cinnamon.
Stir dry ingredients into wet ingredients and then fold in apples.
Spoon or pipe batter into a greased donut pan and bake for about 10 minutes or until a toothpick comes out clean.
Allow to cool completely and then whisk together glaze ingredients. Spread the glaze over top of the donuts or dunk them in and lay it on thick. You can alternatively stir about ½ tsp cinnamon with ½ cup of sugar and coat each donut in the mixture.