Cook the pasta in a pot of boiling water until almost al dente (it's important to not completely cook the pasta as it will continue cooking in the oven). Drain the pasta well, and then place it directly into your baking dish.
Heat the olive oil in a frying pan over high heat. Add the diced chicken, garlic and Italian herbs and cook until the chicken is browned all over and just cooked through. Set to the side then cook through bacon.
Very slowly add the milk (½ a cup at a time), whisking when it is added and as it thickens. Add the grated cheese and season with salt and pepper, whisking until smooth.
Pour the creamy sauce over the pasta and gently mix until all of the ingredients are combined and coated in the cheese sauce. Top with cheese and bake for 30 minutes.