Tomato & harissa stew with cheddar dumplings

INGREDIENTS

• 1 tbsp sunflower oil
• 1 onion , chopped
• 4 celery sticks, thickly sliced
• 400g can plum tomatoes
• 1 tbsp harissa
• 2 large courgettes , halved lengthways and thickly sliced
• 400g can chickpeas , drained
• 1 vegetable stock cube
• 25g butter , diced
• 200g self-raising flour
• 1 tsp baking powder
• 75g extra mature cheddar , finely grated
• 100ml milk