Preheat the oven to 400°F (200°C) and line a baking tray with parchment paper.
In a saucepan, combine the water, milk, butter, and salt. Bring to a gentle boil over medium heat.
Add the flour all at once and stir vigorously with a wooden spoon until the dough forms a smooth ball and pulls away from the sides of the pan, about 2 minutes.
Transfer the dough to a mixing bowl and let it cool for 5 minutes.
Beat in the eggs one at a time, mixing well after each addition until the dough becomes smooth, glossy, and pipeable.
Fold in the grated Gruyère cheese, The Holly Tree Organic Thyme Leaves, Organic Black Pepper Powder, and Organic White Pepper Powder until evenly combined.
Spoon or pipe tablespoon-sized mounds onto the prepared baking tray, leaving about 2 inches between each.
Sprinkle the tops with grated Parmesan for a crisp, golden finish.
Bake for 25–30 minutes, or until the gougères are puffed, deep golden, and crisp on the outside. Avoid opening the oven during baking.