1. In a medium saucepan over medium heat, combine water, milk, butter, sugar, salt and vanilla. Stir until butter is melted and mixture begins to boil. Remove pan from heat and add flour all at once. Mix quickly with a wooden spoon to combine, forming a thick paste.
2. Return saucepan to heat and cook for two minutes, stirring constantly to dry out mixture.
3. Transfer dough to bowl of a mixer fitted with the paddle attachment. Mix for one minute to cool dough. With the mixer running on low speed, add eggs and mix until combined.
4. Transfer the batter to a pastry bag fitted with star tip #847.
5. Lay out parchment squares on your countertop. Pipe a ring of batter onto each parchment square. Continue piping until all batter is done.
6. Heat oil in a medium saucepan to 360 degrees Fahrenheit on a deep fry thermometer. Holding the parchment square at the corner, gently lower a cruller into the hot oil, ridges side down. Remove parchment with tongs and discard.
7. Fry three crullers at a time for about five to seven minutes, turning to ensure even browning. Using a “spider” or slotted spoon, remove from oil to wire rack to drain. Let sit for a minute before tossing in the vanilla-infused sugar.