Creamy Baked Artichoke Chicken Pasta

olive oil, divided

yellow onion, diced

coarse salt and fresh black pepper

fat cloves garlic, thinly sliced

cubed boneless, skinless chicken breasts

Italian seasoning, crushed between fingertips

rigatoni pasta

butter

flour

whole milk

nutmeg

heaping cup grated Parmesan cheese

artichoke hearts, quartered (I use jarred, packed in oil and drained)

mozzarella cheese, shredded