In a medium saucepan, bring water, butter, sugar, and salt to a rolling boil over medium-high heat. Once the butter is fully melted, remove from heat and immediately add all the flour at once. Stir vigorously with a wooden spoon until the mixture forms a smooth ball that pulls away from the sides of the pan, about 1 minute.

Return the pan to medium-low heat and cook, stirring constantly, for 2 to 3 minutes until a thin film forms on the bottom of the pan and the dough looks slightly shiny. This step removes excess moisture so the donuts puff properly.

Transfer the dough to a large bowl and let cool for 5 minutes. Add the beaten eggs in three additions, stirring well after each until fully incorporated. The dough should be thick, glossy, and hold a soft peak when you lift the spoon. If it seems too stiff, beat in a teaspoon of water. Fold in the chocolate chips.

Pour oil into a heavy pot to a depth of 2 inches and heat to 350 degrees F. Line a baking sheet with paper towels and set a wire rack on top.

Transfer the dough to a piping bag fitted with a 1-inch round tip. Pipe 3-inch rings directly into the hot oil, cutting the dough free with kitchen scissors. Fry 3 to 4 donuts at a time, turning once, until deep golden brown and puffed, about 4 minutes total. Maintain oil temperature between 340 and 350 degrees F.

Use a slotted spoon to transfer donuts to the prepared rack. Let cool for 5 minutes, then dust generously with powdered sugar. Serve warm or at room temperature the same day.