Grilled BBQ Chicken Sandwiches with Spicy Avocado Spread

skinless, boneless chicken breast cutlets

barbecue sauce (such as Sticky Fingers Memphis Original)

Cooking spray

slices 2% reduced-fat sharp cheddar cheese

Green leaf lettuce leaves (optional)

Tomato slices (optional)

white wheat hamburger buns

Spicy Avocado Spread