Preheat oven to 400F (200C) and line a large baking sheet with parchment paper. Set aside.

In a medium-sized, heavy-bottomed saucepan, combine water, milk, butter, sugar, and salt and bring to a rolling boil over medium heat.

Once mixture comes to a boil, add flour and turn heat to medium-low. Stir constantly with a spatula until moisture is absorbed by the flour and the mixture clings together and pulls away from the sides of the pot. If you notice any flour lumps, smash them by pressing them against the side of the pan with the spatula.

Remove mixture from heat and stir for several minutes to cool.

Add eggs, one at a time, stirring well after each addition. The mixture will seem to separate at first, but with consistent mixing it will become smooth and velvety.

Stir in ground pepper and gruyere cheese.

Drop batter by rounded dollops about 2” wide and 1” tall onto prepared baking sheet, spacing gougeres at least 2” apart. Transfer to the center rack of 400F (200C) oven and bake for 30 minutes or they are a deep golden brown. If desired, sprinkle a bit of sea salt over the gougeres while they're still warm.

Allow to cool several minutes then serve warm and enjoy!