For the Casserole Base:

• • 2 lbs Yellow Squash (about 4–5 medium squash), sliced: Yellow squash is the star of the show! Choose firm, bright yellow squash with smooth skin. Slicing the squash ensures it cooks evenly and tenderizes perfectly during baking. You can use crookneck or straightneck yellow squash interchangeably. Fresh, in-season squash will offer the best flavor, but you can also use frozen squash, thawed and well-drained, in a pinch (see tips below for using frozen squash).

• • 1 Medium Yellow Onion, chopped: Yellow onion adds a savory depth and aromatic base to the casserole. When sautéed, it becomes sweet and mellow, complementing the mild flavor of the squash. Chopping the onion ensures it cooks evenly and blends seamlessly into the casserole. You can substitute with white or sweet onion for slightly different flavor profiles.

• • 1/2 cup (1 stick) Butter, unsalted: Butter is crucial for richness and flavor in this casserole. It’s used for sautéing the vegetables and adds a luxurious creaminess to the overall dish. Unsalted butter allows you to control the salt level more precisely. You can substitute with salted butter, but reduce the added salt in the recipe accordingly. For a richer flavor, consider using browned butter for sautéing the onions and squash (see variations below).

• • 1 cup Sour Cream: Sour cream is the key to the casserole’s signature creamy and tangy texture. It adds a delightful richness and a subtle tanginess that balances the other flavors. Full-fat sour cream will provide the creamiest result, but you can use light sour cream to reduce the fat content, though it may slightly alter the texture. For a tangier flavor, you can substitute part of the sour cream with crème fraîche or Greek yogurt (though Greek yogurt will be tangier and less rich).

• • 1 cup Mayonnaise: Mayonnaise contributes to the casserole’s creaminess and richness. It also helps to bind the ingredients together and adds a subtle savory note. Use a good quality mayonnaise for the best flavor. You can use light mayonnaise to reduce fat, but full-fat mayonnaise will provide the richest flavor and texture.

• • 1 (10.75 oz) can Condensed Cream of Chicken Soup: Condensed cream of chicken soup adds creamy body and savory chicken flavor to the casserole. It’s a classic ingredient in many Southern casseroles and provides a convenient base for the sauce. You can substitute with condensed cream of mushroom soup or cream of celery soup for slightly different flavor variations. For a homemade option, see tips below for making a cream sauce from scratch. For a vegetarian option, use condensed cream of mushroom or celery soup and ensure your cheese is vegetarian-friendly rennet.

• • 1 teaspoon Salt: Salt is essential for enhancing all the flavors in the casserole. It balances the sweetness of the squash and brings out the savory notes. Adjust the salt amount to your taste.

• • 1/2 teaspoon Black Pepper, freshly ground: Freshly ground black pepper adds a subtle warmth and a bit of spice to the casserole. It complements the other flavors and provides a balanced seasoning. Adjust the amount to your preference.

• • 1/4 teaspoon Garlic Powder: Garlic powder adds a subtle savory garlic flavor to the casserole without being overpowering. It enhances the overall flavor profile and complements the other seasonings. You can substitute with fresh minced garlic, sautéed with the onions and squash, for a stronger garlic flavor (use about 2–3 cloves).

• • 1/4 teaspoon Onion Powder: Onion powder intensifies the onion flavor and adds depth to the casserole. It works synergistically with the fresh onion to create a well-rounded oniony base.

• • 1 cup Shredded Cheddar Cheese, sharp: Sharp cheddar cheese adds a robust cheesy flavor and a beautiful melt to the casserole. Sharp cheddar provides a good balance of flavor and meltability. You can use mild or medium cheddar for a milder cheese flavor, or experiment with other cheeses like Monterey Jack, Colby Jack, or a blend of cheeses. For a sharper flavor, use extra sharp cheddar. Reserve some cheese for topping if desired.

For the Crunchy Topping:

• • 1 cup Crushed Ritz Crackers (about 30 crackers): Ritz crackers are the classic topping for yellow squash casserole, providing a buttery, slightly salty, and wonderfully crunchy texture. Crushing them coarsely allows for maximum crunch. You can substitute with other buttery crackers, breadcrumbs (panko or regular), or even French fried onions for different topping variations (see tips below). For a gluten-free option, use gluten-free buttery crackers or a gluten-free breadcrumb mix.

• • 1/4 cup (1/2 stick) Butter, melted: Melted butter is drizzled over the cracker topping, adding extra richness, flavor, and helping the crackers to brown and crisp up beautifully in the oven. You can use unsalted or salted butter, depending on your preference and the saltiness of your crackers.