Preheat the oven to 350℉. Prepare the donut pan by spraying generously with cooking spray.
In a medium bowl, whisk together the dry ingredients: flour, sugar, cocoa, baking soda, and salt.
1 ½ cup all-purpose flour, 1 cup granulated white sugar, ⅔ cup cocoa, 1 teaspoon baking soda, ½ teaspoon salt
In a smaller bowl, stir together the wet ingredients: milk, oil, vinegar, and vanilla.
1 cup milk, 4 tablespoons avocado oil, 1 tablespoon apple cider vinegar, 2 teaspoons vanilla extract
Stir the wet ingredients into the dry and mix until just combined. Spoon the batter into the prepared donut pans. Another way to fill the pans is by pouring the batter into a plastic bag and cutting a corner off to pipe it into the molds.
Bake for 14-15 minutes (give or take two minutes). The donuts are done when they spring back when touched and will pull away from the edge of the pan slightly.
Leave the chocolate donuts in the pan until they have cooled so that they can be touched without burning fingers. Then invert the pan onto a cooling rack. Dip the donuts upside down into the chocolate glaze. Add sprinkles, if desired!