Sausage and mash pie recipe on Second Nature

Name: Sausage and mash pie recipe on Second Nature
Cuisine: European, British
Ingredients: 650g maris piper potatoes, peeled and diced; 1 tbsp extra virgin olive oil.m; 6 (450g) butcher quality pork Cumberland sausages; 1 braeburn apple, finely diced; 1 small leek, halved lengthways and finely sliced; 2 garlic cloves, finely diced; 1/2 tsp marmite; 1 tbsp Worcestershire sauce; 150ml beef stock; 4 sprigs fresh thyme, leaves only; 2 tbsp butter; 2 tbsp full cream milk; 80g mature cheddar, grated; 1-2 tbsp butter; 200g cavolo nero; 300g asparagus spears; 350g frozen green peas, defrosted