Preheat the oven to 350°F and lightly grease your donut pans.
Mix together the brown sugar, granulated sugar, milk, oil, eggs, and vanilla together in a bowl.
Mix together the flour, cocoa powder, baking soda, baking powder, and salt in a separate bowl.
Combine the wet and dry ingredients together using a whisk until there are no streaks of flour. Do not over mix - some lumps are fine.
Fill a piping bag with the batter, then pipe the batter into the donut pans until they are about ⅔ full.
Bake for about 7 minutes, or until a toothpick comes out clean or with a few crumbs attached.
Remove from the oven and carefully remove the donuts from the pans. Place them on a wire rack to cool.
Make the glaze by heating the chocolate and heavy cream together for at least 30 seconds. Stir well until the chocolate is melted. Heat for another 15 seconds if the chocolate does not fully melt. Slowly drizzle the chocolate onto your powdered sugar, stirring well to avoid lumps. Stir in salt.
Dip the donuts in the chocolate and place back on the wire rack. Top with sprinkles or shaved chocolate.
It helps to gently run a butter knife between the doughnuts and the pan prior to removal.If you get lumps while making the glaze, strain the glaze with a fine mesh strainer. Heating the glaze for 20 - 30 more seconds after adding the powdered sugar also helps with lumps.