Beef Stroganoff Cottage Pie with Crispy Parmesan Topping | Umami

Ingredients

• 800 g (1 lb 12 oz) chuck steak, gravy beef or braising steak (or any beef suitable for slow-cooking), cut into bite-sized pieces
• 1 tsp salt
• ½ tsp cracked black pepper
• 2 tbsp olive oil
• 1 large onion, roughly diced
• 1 tsp garlic, freshly minced
• 400 g (14 oz) mushrooms, sliced
• 2 tbsp plain (all-purpose) flour
• 2 tbsp tomato paste (concentrated puree)
• 1 tbsp sweet paprika
• 1 tbsp Worcestershire sauce
• 1 tsp Dijon mustard
• 2 cups (500 ml) beef stock
• 2 tbsp sour cream
• 1 ⅕ kg (2 lb 10 oz) all-purpose potatoes, peeled and quartered
• 2 tbsp (40 g) unsalted butter
• 1 cup (250 ml) milk, slightly warmed (see note 1)
• Olive oil spray
• ½ cup (50 g) freshly grated parmesan