Squash Casserole

INGREDIENTS

• Kosher salt and freshly cracked black pepper
• 1 small Vidalia onion, chopped (about 3/4 cup)
• Water
• 1 1/4 cups crushed butter crackers, divided
• 1 1/2 cups grated Gruyere cheese
• 1 cup good quality mayonnaise
• 2 pounds yellow squash, cut into 1/2 to 1-inch cubes