Put the saffron in a small bowl and pour over 2 tbsp boiling water. Set aside to infuse. Heat the oil in a large, wide pan, add the chicken and cook for 4-5 minutes.
Tip in the onion and garlic and cook for 3-4 minutes until softened. Add bay leaves and peppers and cook 4-5 minutes more. Stir in peas and broad beans and stir fry for 2-3 minutes. Remove from heat and put aside.
Pour wine into a large saucepan and bring to a simmer. Tip in mussels, cover and cook for 3-5 minutes until mussels open. Discard any that remain closed. Drain over a bowl to catch the liquid. Allow to settle for 5 minutes.
Pour the mussel liquid into the pan with the chicken and veg. Add saffron and chicken stock then cool and chill everything until ready to serve. You can prepare this up to 3 hours ahead.
To serve, cook the tagliatelle as pack instructions. Reheat chicken and simmer for 2 minutes. Add prawns, cook for 1 minute, add cream and cook for 2-3 minutes more. Add mussels, parsley and seasoning. Toss to heat through. Drain tagliatelle and add to the sauce. Serve with lemon wedges and fresh crusty bread.