Skillet Tomato Casserole with White Beans and Parmesan Croutons

extra-virgin olive oil, divided

1/2-inch-diced bread (use a good, crusty whole-grain bakery loaf or sourdough)

fresh tomatoes, cut into a 1/2-inch dice

garlic, minced

sugar

kosher salt

freshly ground black pepper

Great Northern beans, rinsed and drained

ounces frozen chopped spinach, thawed and pressed dry

fresh basil leaves, julienned

freshly grated Parmesan cheese