Preheat your oven to 350°F (175°C). This is the perfect temperature for baking moist donuts.
Lightly grease your donut pan with cooking spray or butter to prevent sticking.
In a large mixing bowl, whisk together the all-purpose flour, dark brown sugar, salt, cocoa powder, and baking powder until well combined.
In another bowl, whisk together the egg, melted unsalted butter, vanilla extract, and chocolate almond milk until smooth.
Pour the wet ingredients into the bowl with the dry ingredients. Stir gently until just combined; be careful not to overmix.
Using a piping bag or a spoon, fill each donut cavity about three-quarters full with batter.
Place the donut pan in the preheated oven and bake for 10-12 minutes, or until a toothpick inserted into the center comes out clean.
Once baked, remove the pan from the oven and let it cool for about 5 minutes. Then, carefully transfer the donuts to a cooling rack to cool completely.
In a medium bowl, combine the confectioners' sugar, cocoa powder, heavy cream, and a pinch of salt. Whisk until smooth.
Once the donuts are completely cool, dip the tops into the glaze, allowing any excess to drip off.
While the glaze is still wet, sprinkle rainbow sprinkles on top for a festive touch!
