Preheat oven to 425°F and grease donut pan. In a large bowl, sift together flour, sugar, baking powder, cinnamon, and salt. Whisk in milk and egg, mixing until just combined. Fill each cup about 2/3 full. Bake for 8 minutes. Flip donuts onto a rack and let cool.
Meanwhile, melt butter in a small saucepan over medium heat. Stir in the brown sugar and cream and whisk until the sugar is completely dissolved.
Increase heat slightly and bring the mixture to a light boil. Cook for 5-8 minutes, stirring occasionally. Whisk in vanilla and remove from heat. Let cool until ready to use. (This can be done ahead of time and stored in the fridge.)
Toast coconut by pouring it into a dry skillet over medium heat and stirring often, until it is nicely browned. Set aside until ready to use.
Melt chocolate in a microwave safe bowl at 30 second intervals, stirring between intervals, until chocolate is melted and smooth.
Dip bottom of donut in chocolate and use a spoon to cover bottom as needed. Set chocolate-side up onto a wire rack or a lined plate. Repeat with remaining donuts.
Set the rack or plate into the freezer for 5-10 minutes, until chocolate is hardened.
Dip tops of donut into butterscotch sauce, and set back onto rack or plate. Sprinkle coconut on donuts, then, using a fork, drizzle remaining melted chocolate over the tops in lines. Let toppings firm up in the fridge, or enjoy at room temperature.