Cook pasta according to packet directions (I only add a very small pinch of salt to the water) minus 1 min, then drain & return to pot, adding 2 teaspoon of butter and stirring lightly to coat
While pasta is cooking, place bacon in a small non-stick fry pan/skillet and fry for 6-8 mins, then add garlic and rosemary to pan & continue to fry for 1 min then remove pan from heat
Add bacon mixture to cooked pasta & stir lightly to mix, then add cream & shredded parmesan to pasta, mixing to coat, then add chicken & mix again until incorporated
Tip chicken and pasta mixture into an a baking dish, top with shredded mozzarella and bake uncovered for about 20 mins, or until peaks are lightly browned, then serve immediately