Grandma's Squash Casserole | Cooking Professionally

Ingredients

• 6 tablespoons unsalted butter, divided
• 3 pounds yellow squash, sliced 1/4-inch-thick
• 1 1/2 cups yellow onion, chopped
• 2 teaspoons kosher salt, divided
• 2 large eggs, lightly beaten
• 1 (8-ounce) container sour cream
• 1 cup sharp cheddar cheese, shredded
• 1/2 cup Swiss cheese, shredded
• 1/2 cup mayonnaise
• 2 teaspoons fresh thyme, chopped
• 1/2 teaspoon black pepper
• 2 sleeves round butter crackers, coarsely crushed
• 1/4 cup parmesan cheese, shredded