Cheesy Baked Chicken Penne

butter, plus more for baking dish

coarse salt and fresh black pepper

penne pasta

olive oil

boneless, skinless chicken breasts, cut in half

all-purpose flour

garlic cloves, minced

whole milk

diced tomatoes, drained well and chopped into small pieces

+ 1/2 cups mozzarella cheese, shredded

Parmesan cheese, grated, divided