Preheat the oven to 400F and line two baking sheets with parchment paper. 

Combine butter, milk, water and salt in a medium-sized pot. Bring to a boil over medium heat and add all the flour at once. 

Stir briskly until a smooth dough forms. Continue stirring until the dough pulls away from the side of the pan and a thin film forms on the bottom of the pan, about 2 minutes. Stir for another minute or so to make sure the dough is dry and remove from heat. 

Let dough cool for 2 minutes, stirring once or twice to release steam. Add eggs one at a time, beating after each addition to thoroughly incorporate. Add cheese and juniper berries and mix thoroughly. 

Using two spoons, drop dough spaced two inches apart onto the baking sheets. (For bite-sized pieces use teaspoons; for bigger pieces use soup spoons. If you’re handy with a pastry bag, spoon the mixture into the bag and pipe onto the baking sheets using a ½-inch tip.) 

Sprinkle reserved cheese over top and bake for 20 to 25 minutes, until puffed and golden. The gougères will sound hollow when tapped.