Chicken chasseur

Name: Chicken chasseur
Prep time: 15 min
Cook time: 1 h 50 min
Total time: 2 h 5 min
Cuisine: French
Ingredients: 2kg chicken thighs and drumsticks; 4 tbsp plain flour; 1 tbsp olive oil; 1 tbsp butter; 2 long shallots, diced; 250g button mushrooms; 3 cloves garlic, crushed; 2 tbsp tomato purée; 250ml white wine; a few sprigs thyme; 2 bay leaves; 600-800ml chicken stock; 2-4 tbsp (optional) cornflour; flat-leaf parsley or chervil, a handful, chopped; 1 bulb garlic; 2 tsp olive oil; 1.5kg floury potatoes; 50ml double cream; 100ml whole milk; 50g salted butter; 50g parmesan, gruyère or comte, finely grated, plus extra to serve