Ultimate Cheesy Squash Casserole

Name: Ultimate Cheesy Squash Casserole
Prep time: 20 min
Cook time: 30 min
Total time: 50 min
Cuisine: American, Southern
Ingredients: 2 pounds yellow squash, thinly sliced (about 1/4-inch thick); 1/2 sweet onion, finely diced; 3 tablespoons bacon grease (or butter); 1 teaspoon salt; 1/2 teaspoon black pepper; 1 (10.5-ounce) can cream of chicken and mushroom condensed soup ((see note)); 1/2 cup sour cream; 2 cups shredded sharp cheddar cheese; 1/4 cup unsalted butter, melted; About 30 buttery crackers, crushed (like Ritz)