Layered Squash and Tomato Casserole

slices of bacon

to 4 small to medium summer squash , sliced about 1/4" thick*

Vidalia or other sweet onion , coarsely chopped

to 3 tomatoes , coarsely chopped

Garlic salt

Kosher salt and freshly cracked black pepper

shredded cheddar

Panko bread crumbs

Olive oil , to drizzle

Chiffonade of fresh basil , for garnish, optional