Savoury Crayfish Éclairs

Name: Savoury Crayfish Éclairs
Prep time: 45 min
Cook time: 1 h 20 min
Total time: 1 h 20 min
Yield: 16 pieces
Ingredients: 30 g Parmesan cheese; 80 g unsalted butter; 150 g water; 2 pinches mustard powder; 1 - 2 pinches cayenne pepper; ¼ tsp fine sea salt; 120 g plain flour; 3 medium eggs; 240 g crayfish; 110 g mayonnaise; 1 lemon; 1 ½ tsp Dijon mustard; 2 pinches ground cayenne pepper; 2 pinches fine sea salt; 1 pinch ground black pepper; 20 g rocket leaves