Cheesy and Flavorful Squash Casserole

Ingredients

• 2 pounds yellow squash, sliced
• 1/2 cup onion, chopped
• 2 tablespoons butter
• 1 cup shredded cheddar cheese
• 1/2 cup sour cream
• 1/2 cup mayonnaise
• 1 tablespoon Dijon mustard
• 1/2 teaspoon garlic powder
• 1/2 teaspoon salt
• 1/4 teaspoon black pepper
• 1 cup breadcrumbs
• 2 tablespoons butter, melted