Toss the torn sourdough in the olive oil and place under broiler for 6-7 minutes, until fully toasted. Remove and allow to cool. Pulse in a food processor until crumbs have formed. Toss the crumbs with Italian seasoning and salt. Set aside.
Preheat oven to 375 degrees F.
Cook pasta according to directions BUT 1 minute less than instructed. Once it’s done, save 1/2 cup pasta water and strain the rest and put the pasta in a large casserole dish.
Heat the butter and olive oil until melted. Whisk in the flour. Once the clumps are gone, slowly whisk in the milk and heavy cream.
Bring mixture to a boil, whisking constantly. Once it boils, bring heat down to simmer and stir/whisk until mixture has thickened - about 4-5 minutes.
Stir in the cheese and the spices. Stir until cheese is melted and add in the saved pasta water. Pour the cheese sauce over the pasta in the casserole dish.
Add your chicken and broccoli to the mac-n-cheese and mix everything well. Top with the breadcrumbs and freshly shredded parmesan reggiano. Bake for 12-14 minutes.