Preheat oven to 350 degrees. Spray donut pan with nonstick coating and set aside.
Sift flour, baking powder, baking soda, brown sugar and salt together in a large bowl.
In a separate bowl, whisk egg, milk, yogurt, melted butter, vanilla and maple syrup until combined.
Carefully add wet ingredients to dry, stirring with a wooden spoon until just combined. Take care to avoid overmixing. Note: Batter will be thick.
Pipe batter into donut pan, evenly distributing between eight cavities.
Bake for 9 minutes. Donuts are done when tops spring back when pressed by a fingertip.
Cool donuts in pan for 3 minutes then remove to a wire rack to cool completely before adding glaze.