1. Put a large pan of salted water on to boil. Heat your grill to high. When the water is boiling, add the pasta. Simmer for 8 mins, then drain.
2. While the pasta is cooking, tip the sun dried tomatoes into a heatproof bowl. Pour over enough boiling water to cover them and set the bowl aside to let them soak.
3. Warm a large, deep ovenproof frying pan for 1 min. Add 2 tsp olive oil and the chicken. Fry over a medium heat, turning once or twice, for 8-10 mins till golden all over. If you don't have an ovenproof frying pan that will go under your grill, spoon the pasta and sauce into an heatproof dish. Top with the mozzarella and breadcrumbs and grill, following the recipe.
4. While the chicken is frying, trim the ends off the courgette then dice it. Trim the roots off the spring onions and finely chop them. Peel and crush the garlic. Finely chop most of the sage leaves.
5. Lift the chicken out of the pan and pop on a plate. Add the courgette and spring onions to the pan with 2 tbsp water. Season with a pinch of salt and pepper. Cook and stir for 5 mins to soften the veg. If the pan dries out and they start to catch, add a splash more water.
6. While the vegetables fry, drain the mozzarella and coarsely grate it.
7. Return the chicken to the frying pan. Stir in the garlic, chopped sage and cream. Take off the heat. Stir in the drained pasta. Drain the sun dried tomatoes, roughly chop and stir them in too. Taste and add more salt and pepper if it needs it.
8. Sprinkle over the grated mozzarella and the breadcrumbs. Slide under the grill for 10 mins till the mozzarella is golden and bubbling.
9. While the pasta gratinato grills, whisk 1 tbsp balsamic vinegar with 2 tsp olive oil and some salt and pepper to make a dressing. Toss the salad leaves with the dressing. Serve the pasta bake in warm bowls, garnished with the remaining sage and with the salad on the side.