Cheesy Chicken and Potato Casserole

Ingredients

• 3 (7 oz or 200 g) baking potatoes, peeled and cubed
• 1-1/2 cups (13.4 fl oz or 375 ml) water
• 1 pound (450 g) cooked chicken breast fillet, diced
• 1/2 cup (4 oz or 125 g) sour cream
• 1/2 cup (2 oz or 60 g) cheddar cheese, grated
• 2 tablespoons (1 oz or 30 g) unsalted butter, melted
• 1/4 cup (1 oz or 30 g) Parmesan cheese, grated
• 1 envelope (1 oz or 30 g) onion soup mix
• 1/2 teaspoon (1 g) garlic powder
• 1/4 cup (1 oz or 30 g) breadcrumbs
• kosher salt and freshly ground black pepper