Here are a couple of variations on that old standby, the casserole made with yellow squash and/or zucchini squash, a good way to use up bounty from the garden.

This first one is from a cookbook published by Garvin County Home Demonstration Clubs in Oklahoma, sometime in the mid 1960s.

Baked Squash with Cream Sauce
1 to 1 1/2 pounds sliced summer squash
1 medium onion, diced
Salt
Cream sauce:
2 tablespoons butter
2 tablespoons flour
Milk to make a sauce
5 oz Longhorn (or other) cheese, shredded
Saltine crackers, crumbled

Simmer the squash and onions in a little salted water until the squash is tender. Make the cream sauce. In a casserole, make layers of squash, crackers, cream sauce, and then grated cheese. Use plenty of cream sauce and end up with cheese on the top. Bake in a 350 oven until brown.

This next one is from Pepperidge Farm, so it's got stuffing mix in it.

Squash Casserole with Stuffing
3 cups herb seasoned stuffing
1/4 cup margarine (or butter), melted
1 can (10 3/4 ounces) cream of chicken soup
1/2 cup sour cream
2 small yellow squash, shredded
2 small zucchini, shredded
1/4 cup shredded carrot
(Diced green chilies)
1/2 cup shredded cheddar cheese (2 ounces)

Mix stuffing and margarine. Reserve 1/2 cup stuffing mixture. Spoon remaining stuffing mixture into 2 quart shallow baking dish. Mix soup, sour cream, squashes, carrot, diced green chilies if desired, and cheese. Spread over stuffing mixture. Sprinkle reserved stuffing mixture over soup mixture. Bake at 350 degrees for 40 minutes or until hot.

Here is an Italian version from Buddy, the Cake Boss on the Food Network. He has/had a show called "Kitchen Boss" that I liked more than the show about his bakery.

Italian Squash Casserole

2 each medium zucchini and yellow squash, approximately 2 pounds
1 teaspoon salt
1/4 cup sun dried tomato pesto
1 Tablespoon chopped oregano
1 Tablespoon chopped parsley
1/4 cup good olive oil
1‑2 large shallots, thinly sliced lengthwise
1 cup bread crumbs (see below)
1‑1/2 cups shredded Fontal or Bel Paese

Preheat oven to 400°. Thinly slice (less than 1/4") the zucchini and yellow squash into circles. Toss squashes with salt and let sit in colander to drain 15 minutes. Pat dry. In a large bowl, stir together the pesto, herbs, olive oil and shallots. Add the squash and combine all well. Pour into an 8" x 12 1/2" shallow baking dish (or similar capacity). Cover with foil and bake 20 minutes.
In the same bowl you used to toss the squash, and without wiping out, toss the bread crumbs and cheese together, absorbing the oil left in the bowl.
Remove the foil from the squash and top with the crumb/cheese mixture. Bake and additional 20 minutes, uncovered. Let rest 10 minutes before serving.

Buddy's Bread Crumbs
Crumbs
1 lb loaf rustic Italian bread
1 cup finely grated pecorino romano cheese
2 garlic cloves, put through a garlic press
2 tablespoons dried Italian herb seasoning
3 tablespoons dried parsley flakes
1/2 tablespoon fine sea salt
The day before you plan too make breadcrumbs slice the bread into 1/2 inch slices. Place slices on cake racks to dry overnight. In batches, crumble or tear bread slices into the bowl of a food processor fitted with the steel blade. Pulse the bread multiple times until the crumbs are about the size of a dime. Add the cheese, garlic, herbs and salt and continue to pulse until the breadcrumbs become fine. Store what you are not using in the freezer or in your refrigerator for 3-4 days.