1. Peel and thinly slice the onion. Transfer it to a microwaveable container with the butter. Cover and cook at 750W for 5-6 minutes.
2. Add the stock and bay leaf and cook for a further 5-6 minutes, until the soup begins to boil. Season with salt and pepper.
3. Divide the soup between two soup dishes and sprinkle with 40g grated Parmesan.
4. Place the dishes in the microwave, one at a time, on the top shelf and cook using the grill function until the cheese has melted and the top is a golden brown colour.
5. Serve with two slices of bread per person.
12 minutes minutes