In a large bowl, combine the flour, active dry yeast, sugar, salt, and cocoa powder together until mixed evenly.
Make a well in the center of the mixture and add oil and lukewarm water. Mix with hands until all ingredients have come together to form a ball of dough.
On a lightly floured surface, knead the dough for about 5 minutes until it has become smooth and elastic. Cover the bowl with plastic wrap and let the dough sit in a warm place for 1 hour.
After an hour, roll out the dough on a lightly floured surface to about 1/4-inch thickness. Use a cookie cutter or biscuit cutter to cut out the donuts.
In a large skillet over medium heat, pour in enough oil for deep-frying. Once the oil is hot enough, gently drop the cut donuts into the oil and fry for about 2 minutes on each side.
Remove the donuts from the oil and let them cool slightly before topping with grated chocolate, chopped nuts, sprinkles, or hot whipping cream.