Slow cooker shepherd's pie - Good Food Middle East

Ingredients

• 1 tbsp olive oil
• 1 onion, finely chopped
• 3-4 thyme sprigs
• 2 carrots, finely diced
• 250g lean (10%) mince lamb or beef
• 1 tbsp plain flour
• 1 tbsp tomato purée
• 400g can lentils, or white beans
• 1 tsp Worcestershire sauce
• 650g potatoes, peeled and cut into chunks
• 250g sweet potatoes, peeled and cut into chunks
• 2 tbsp half-fat crème fraîche