In a medium pot, stir together the milk, water, butter, salt and dessert sauce and bring to a slow boil over medium heat, stirring often. When the butter has melted and the mixture has become uniform, stir in the flour and cocoa powder with a wooden spoon until a dough is formed. Reduce heat to low and continuously stir for 5 minutes. This process is similar to kneading the dough, so be sure to stir well while it is cooking.
Transfer the dough to the bowl of an electric mixer. Using the paddle attachment, beat the dough on low-medium until the dough has cooled and bowl is no longer hot to the touch (about 5-10 minutes).
Add one egg at a time ensuring it is fully incorporated before adding the next one, scraping the sides of the bowl as necessary. Add egg white and mix until the dough is sticky and uniform. Cover and set in the refrigerator for at least 1 hour.
Cut 16, 3”x 3” squares of parchment paper and set aside. Set a cooling rack on top of a baking sheet lined with paper towels.
Heat oil in an electric fryer or in a heavy, deep, non-reactive pot to 350° F.
While the oil is heating, fill a large piping bag fitted with a large star tip with the chocolate dough mixture. Spread out the parchment squares and pipe one circular cruller onto each square. Smooth where the cruller comes together with your finger tip if needed.
When the oil is to temperature, very gently lower a cruller into the oil while still on the paper. Allow to fry for 1-2 minutes and then gently remove the parchment paper with a pair of metal tongs. Continue to fry an additional 2-3 minutes and then flip over and fry an additional 4 minutes. Remove from oil and set on the cooling rack. Continue until all crullers are fried.