Creamy Pork and Apple Casserole with Cider

Name: Creamy Pork and Apple Casserole with Cider
Prep time: 15 min
Cook time: 2 h 10 min
Total time: 2 h 25 min
Cuisine: British
Ingredients: 2 tbsp olive oil; 500 g (1.1 lbs) pork shoulder steaks (chopped into large chunks); 1/2 tsp salt; 1/2 tsp pepper; 1 medium onion (peeled and diced); 12 button mushrooms (sliced in half); 2 cloves garlic (peeled and minced); 2 tbsp plain (all-purpose) flour; 240 ml (1 cup) dry cider; 420 ml (1 3/4 cups) chicken stock; 1/2 tsp dried sage ((or 1 tbsp finely chopped fresh sage)); 2 crisp dessert apples; 80 ml (1/3 cup) double (heavy) cream; 6 fresh sage leaves ((optional)); 1 apple (cored and thinly sliced)