Preheat oven to 355 degrees F.

Heat the milk, water, sugar, salt, and butter in a medium-sized pot over medium heat, stirring occasionally.

Once the mixture reaches boiling point, remove from the heat, and add the flour to the pot. Mix together until well combined.

Return the pot to medium heat. Cook  stirring constantly until the mixture comes together, and no longer sticks to the bottom or sides of the pan, approx. 4-5 minutes.

Transfer dough to a stand mixer bowl. Mix using the paddle attachment on medium speed. Pour about one quarter of the whisked eggs into the bowl. Beat until smooth and homogenous. Continuing add remaining egg mixture at a time in stages. Repeat this process until the dough is ready (see Tips section for more information on this).

Add the cayenne pepper and grated gruyere cheese to the bowl, and beat until well mixed.

Transfer the mixture to the piping bag equipped with a plain tip.

Pipe the dough into dome shapes on to a silicone baking mat in a baking tray.

Brush with an egg wash before baking.

Bake for 35 minutes, or until golden brown. Serve slightly warm and enjoy!