Butternut Squash Gratin without wheat breadcrumbs

1 -2 medium butternut squash 2 tablespoons olive oil 2 (14 ounce) cans diced canned tomatoes (plain or with basil, oregano) 2 cups cheddar cheese , shredded 1[...]

1 butternut squash (approximately 2lb) 1 tablespoon butter 1 onion , thinly sliced (sweet is best) 2 tablespoons flour 1/4 teaspoon pepper 1 cup chicken broth[...]