Preheat your oven to 350°F (175°C).
In a large mixing bowl, combine the self-rising flour, cocoa powder, protein powder, and granulated sweetener. Whisk until well combined.
In a separate bowl, mix the sunflower oil and almond milk until well blended.
Pour the wet mixture into the dry ingredients. Mix gently until just combined.
Lightly grease your donut pan. Spoon the batter into each mold, filling them about 3/4 full.
Bake for 10-12 minutes, or until a toothpick inserted into the center comes out clean.
Let the donuts cool in the pan for about 5 minutes before transferring them to a cooling rack.
In a medium bowl, combine the powdered sugar substitute, cocoa powder, and milk. Mix until smooth.
Dip the tops of the cooled donuts into the glaze or drizzle it over the top. Allow the glaze to set before serving.