Gather the ingredients.
Combine the butter, water, milk, and salt in a medium saucepan over medium heat until the mixture comes to a boil and the butter melts.
Take off of the heat and add the flour, stirring with a flexible spatula until combined.
Return the pan to the heat over medium heat and cook the dough until it becomes glossy and thickens, stirring constantly. The dough is ready when it begins pulling away from the bottom of the pan, about a minute or two.
Transfer the dough to a mixing bowl and stir to cool.
Whisk the eggs together in a measuring cup and add a little egg at a time to the dough, stirring after each addition, until the dough is smooth, soft, and silky. When you lift up your spatula the dough should hang off the end.
Cut parchment paper into twelve 3-inch squares and place the squares on a baking sheet.
Fill a large pot with 2 inches of oil. Clip a thermometer to the side of the pot and heat the oil on medium to medium-high heat until it reaches 350 F.
Fill a piping bag fitted with a large fluted tip with the dough and pipe 3-inch circles on to the parchment paper squares.
Transfer 3 to 4 crullers, still on the paper, to the oil. The paper will release from the crullers and you can remove it with tongs.
Fry for about 30 seconds and then flip the crullers over. This helps them retain their ridged appearance. Once flipped, watch the crullers closely and once they start to crack, which they will, do not be alramed.
Fry for about 2 1/2 more after the first crack and then flip them back over for 2 minutes or so, about 3 to 4 minutes total for each side. A nicely browned color is what you are after.
Transfer the crullers to a cooling rack lined with paper bags or paper towels. Let cool before glazing.
To make the glaze, combine the confectioners' sugar, milk, and vanilla in a shallow bowl and whisk to combine.
Dip the crullers into the glaze, one at a time. Glaze both sides or only one, depending on how sweet you like your donuts. Let the glaze set a few minutes before eating. Enjoy immediately.