In a large bowl, whisk together the flour, baking powder, salt, spice and sugar.
Whisk together all of the remaining ingredients (except for the canola oil) in a second, medium bowl.
Make a well in the center of the dry ingredients. Pour the wet ingredients into the dry ingredients, and stir them around the bowl until the mixture is well combined.
Turn out onto a lightly floured surface, rolling the donut dough to approximately1/4-1/2″ thick. (I know this will seem quite thin, but the donuts puff up immensely while frying). Cut with a donut cutter.
Meanwhile, whisk the glaze ingredients together in a small bowl until smooth.
Heat 2 inches of oil in a large skillet over medium-high heat. When the oil is hot, gently slide the donuts into the oil, frying on the first side until the edges of the donut are lightly browned, flip carefully and allow to cook on the other side until lightly browned.
Remove and dunk immediately into buttermilk glaze. Allow to air dry on a cooling rack before serving.