Preheat oven to 425˚F. Line a baking sheet with parchment paper.

Combine water, milk, butter, sugar, and salt in a medium pan.

Bring to a slight boil over medium-high heat. As soon as it boils, please remove it from the heat to stop the cooking.

All at once, stir in the flour and mix with a wooden spoon until incorporated.

Place the pan back over medium-high heat, constantly stirring for 2 to 3 minutes to release moisture, and start cooking the flour. A film will form on the bottom of the pan, and the dough will create a smooth ball.

Transfer dough to the bowl of a stand mixer, and mix on medium speed for a minute so the mixture can cool slightly.

Add eggs, one at a time, mixing on medium speed, allowing each egg to incorporate between additions.

Beat a minute longer until the dough is smooth and forms a ribbon when the paddle is pulled up.

For puff style choux, Fill a piping bag with a 1/2" round tip with the dough. Pipe in two-inch circles.

For Éclair style choux, Fill a piping bag with a 1/2" round tip with the dough and pipe in a four-inch line.

Bake at 425˚F for 10 minutes in the center of the oven. Without opening the oven, reduce the temperature to 325˚F and bake 20-22 min longer or until golden brown on top.

Transfer to a wire rack to cool completely.