Fish pie with mashed potato topping

Name: Fish pie with mashed potato topping
Prep time: 30 min
Cook time: 2 h
Total time: 2 h 30 min
Cuisine: European, British
Ingredients: 30 g olive oil; 500 g boneless white fish fillets; 120 g smoked salmon; 250 g cherry tomatoes; 2 pinches sea salt; 2 pinches ground black pepper; 1 brown onion; 1 leek; 120 g bacon; 3 - 5 sprigs fresh flat-leaf parsley; 30 g unsalted butter; 30 g plain flour; 130 g water; 1 tsp Vegetable stock paste; 70 g sour cream; 50 g Parmesan cheese; 1000 g floury potatoes; ½ - 1 tsp salt; 250 g full cream milk; butter; 1 - 2 pinches ground nutmeg