Cut the butter into small pieces
Put the water, milk, and butter in a saucepan and warm for a few minutes.
Once off the heat, add the flour to the bowl with the water and melted butter and bat vigorously till smooth.
Let the mixture cool for a few minutes.
Add the eggs one by one, mixing well.
Add the grated Gruyere, nutmeg, salt, pepper and cayenne pepper to the mixture.
Mix thoroughly until it has a doughy consistency.
Pre-warm the oven at 400°F (200°C).
Make small round balls with the dough using a cookie scoop or your hands, and place on a lined baking tray.
Place in the oven and bake for 25 minutes until golden brown.
Remove from oven and serve.