Fish Pie with Dubliner Cheese Rösti Topping from Clodaghs Suppers

Name: Fish Pie with Dubliner Cheese Rösti Topping from Clodagh’s Suppers
Ingredients: 1 pound Idaho or Russet potatoes; 2 ounces aged Dubliner cheese; 9 ounces skinless smoked haddock fillet; 9 ounces skinless salmon fillet; 3 ½ ounces raw, peeled shrimp; 1 ¼ cups whole milk; 1 shallot, peeled and halved; 1 bay leaf; 1 teaspoon black peppercorns; 5 tablespoons butter, softened ‘; ½ cup all-purpose flour; 2 teaspoons Dijon mustard; Sea salt and freshly ground black pepper; 2 tablespoons chopped dill