French Cheese Puffs (Gougeres)

Bahan-bahan (24 porsi)

• 1 cup (250ml) water
• 80 g / 5.5 tbsp butter (, unsalted, cut into 1.5 cm / 0.5" cubes)
• 1 cup (150g) flour (, plain / all purpose)
• 3/4 tsp salt (, kosher/cooking salt)
• Pinch nutmeg ((powder or freshly grated))
• Pinch black pepper
• 4 eggs ((~60 - 65g / 2oz each))
• 200 g / 2 cups Gruyère cheese (, freshly shredded (Note 1))
• 50 g / 1/2 cup Gruyere cheese, extra (, freshly shredded (Note 1))
• 1 egg yolk (, for brushing)