01 - Preheat the oven to 350°F. Lightly grease a donut pan with butter or nonstick spray.
02 - In a large bowl, whisk together flour, cocoa powder, sugar, baking powder, baking soda, and salt.
03 - In a separate bowl, beat eggs, then add milk, melted butter, and vanilla extract. Stir until fully combined.
04 - Pour the wet ingredients into the dry ingredients and gently stir until just combined, avoiding overmixing.
05 - Transfer batter to a piping or zip-top bag and pipe evenly into the prepared pan, filling each cavity about three-quarters full.
06 - Bake for 10 to 12 minutes or until a toothpick inserted in the donuts comes out clean.
07 - Allow the donuts to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.
08 - Whisk powdered sugar, cocoa powder, milk, and vanilla until smooth.
09 - Dip cooled donuts into the glaze, letting excess drip off, then return to the wire rack to set.