Sweet beans pie recipe

Ingredients

• 1 kg sweet potatoes
• 25 g butter or margarine
• 1 tbsp olive oil
• 1 medium onion, finely chopped
• 1 410g tin chopped tomatoes with juice
• 200 ml vegetable stock
• 0.5 tsp dried thyme
• 1 tsp yeast extract
• 1 tsp soy sauce
• 2 cans of mixed beans of your choice such as kidney beans, butter beans or baked beans (410g each)
• 50 g grated cheese