1. Heat 4 tbsp butter in a deep skillet and saute the chicken and onion until golden brown.

2. Add the rice, stir well, and cook for 15 minutes.

3. Heat the stock until boiling.

4. Gradually add the stock to the rice.

5. Add the white wine, saffron, salt, and pepper to taste and mix well.

6. Simmer gently for 20 minutes, stirring occasionally, and adding more stock if the risotto becomes too dry.

7. Leave to stand for a few minutes.

8. Add a little more stock and simmer for a further 10 minutes.

9. Serve sprinkled with Parmesan cheese and the remaining butter.