tasty white fish crumble casserole

Ingredients

• 1 pound white fish fillets
• 1 1/4 cups milk
• - salt and freshly ground black pepper to taste
• 1 tablespoon sunflower oil
• 1/2 cup butter
• - 1 medium onion, peeled and finely chopped
• - 2 leeks, sliced
• - 1 medium carrot, peeled and small diced
• - 2 medium potatoes, peeled and cut into small pieces
• 6 tablespoons all-purpose flour
• 1 1/2 cups fish or vegetable stock
• 2 tablespoons whipping cream
• 1 teaspoon freshly chopped dill
• 1/2 cup butter
• 1/2 cup all-purpose flour
• 3/4 cup grated parmesan cheese
• 3/4 teaspoon cayenne pepper