Donut dough: Combine all the ingredients except the butter on the bowl of a stand mixer with the dough hook attachment. Mix for 5 minutes on first speed. Knead for 10 minutes on second speed, then add in the cold butter and knead until the dough does not stick to the sides of the bowl. Add the chocolate chips and mix just until they are incorporated. The temperature of the dough should be about 75°F (24°C). Cover with plastic film and allow to rise for 2 hours at room temperature. Beat down the down and flatten on a plastic film lined baking tray. Cover and place in the freezer for 30 minutes to stop fermentation. If dough is to be used immediately, store in the refrigerator, otherwise the dough can be stored in the freezer for up to 2 weeks.

Cocoa nib sugar: Process sugar and cocoa nibs in a spice grinder to achieve a fine texture. Sieve out any large pieces and re-grind if necessary.

Assembly: Portion dough into 20 grams pieces and roll to balls, or roll out to a thickness of 1 cm and cut with a 7 cm round cutter and then a 3.5 cm cutter for a traditional donut shape. Allow to proof at 77°F (25°C) for 2 hours, or until dough has doubled in volume. Bake at 350°F (175°C) to golden brown. Toss in cocoa nib sugar and serve immediately.