Mix the Donut Batter:
Preheat your oven to 350°F (175°C) and grease a donut pan. In a large bowl, whisk together the sugar, vegetable oil, milk, and eggs. Sift in the cocoa powder, flour, baking powder, and salt, then stir until just combined and no streaks of flour remain.

Bake the Donuts:
Pipe or spoon the batter into the prepared donut pan, filling each cavity about two-thirds 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 a few minutes before transferring them to a wire rack to cool completely.

Create the Chocolate Glaze:
Melt the dark chocolate chips in a microwave-safe bowl in 30-second intervals until smooth. In a separate small bowl, melt the white chocolate chips in the same manner.

Decorate Your Spiderweb Donuts:
Dip the top of each cooled donut into the melted dark chocolate. While the glaze is still wet, use a piping bag to draw 3-4 concentric circles with the melted white chocolate. Immediately use a toothpick to drag lines from the center outwards to create a spiderweb effect. Let the chocolate set completely before serving.