Pre-heat oven to 350° (180° celsius). Grease and flour a 6 donut pan.Melt butter and let cool.In a large bowl whisk together flour, baking powder, baking soda, salt, sugar and cinnamon.In a medium bowl whisk together, egg, yogurt, milk, vanilla, apple butter and cooled butter until smooth.Mix wet ingredients into dry ingredients, until combined. Spoon into prepared donut pan or pour into a pastry bag and pour into donut pan. Bake for approximately 10 minutes. Let cool completely before dipping in frosting.
In a small bowl combine powdered sugar, vanilla and maple syrup if it is too thick add 1/2 tablespoon of milk, mix until smooth.