In a medium heavy-bottomed saucepan, combine the milk, water, butter, sugar, and salt. Cook, stirring, until butter melts and mixture just comes to the boil. 

Remove from heat. Add all the flour to the butter mixture at once, beat until well combined.

Return the pan to heat and cook for 2-3 minutes, stirring vigorously the entire time. The mixture will form a ball and begin to come away from the side of the saucepan.

Remove from heat and transfer to the bowl of a stand mixer fitted with a paddle attachment or a large mixing bowl if using a handheld mixer. Set aside for 15 minutes to cool.

Mix the dough while adding 2 eggs. Beat on medium speed until the eggs have been fully incorporated. Add the third egg. Beat on medium until fully incorporated. Then add the egg white. Beat once again until fully incorporated.

Cover the bowl with plastic wrap and let chill in the fridge for 10 minutes.

Cut out 15 3*3-inch squares of parchment paper.

Fill a heavy-bottomed saucepan or cast iron dutch oven with about 3-4 inches of oil. Heat to 350-370°F.

Remove the dough from the fridge and transfer it into a pastry bag fitted with a large star tip. Holding the pastry bag vertically over one of the parchment squares, pipe an even circle of dough, just making ends meet.

Gently place a cruller onto a slotted spoon, along with its paper, and lower it into the hot oil. Fry the crullers 3 or 4 at a time, removing the paper with tongs after 1 minute and flipping them over. Fry for approximately 6 minutes, turning to ensure even cooking, until golden brown.

Remove from the oil and allow to drain on the wire rack. Cool before glazing.

To make the glaze, put the chocolate and butter in a microwave-safe bowl and microwave for about 40-60 seconds, or until the chocolate and butter are melted and smooth. Stir the powdered sugar into the melted butter and chocolate. Beat the mixture, adding small amounts of hot water until thinned as desired.

Dunk one cruller at a time in the glaze, allow the additional glaze to drip off, and then place on the wire rack. Top with sprinkles.

Enjoy!