Slow braised beef short ribs with cheesy mash

• 2 kg/4 pounds beef short ribs I prefer using bone-in short ribs cut into smaller pieces but you can use larger pieces as well
• 2 onion finely chopped
• 3 carrot peeled and finely chopped
• 2 celery finely chopped, sticks
• 6 garlic finely chopped, cloves
• 2 tbsp flour (optional)
• 2 pieces rosemary fresh
• 1 bay leaf
• 1 cup tomato puree or passata
• 2 cups beef stock
• 2 cups red wine
• 500 g/1 pound mushrooms
• salt to taste
• black pepper to taste

For the cheesy mash

• 1 kg/2 pounds potato peeled and quartered
• 2 tbsp butter
• ½ cup milk
• 1 cup cheddar cheese grated
• salt to taste
• black pepper to taste