On a large baking sheet place baguette slices in a single layer. Toss cheese with walnuts and seasoning and press equal amounts very firmly onto each baguette slice. Coat liberally with cooking spray.
Heat a large nonstick skillet over medium heat. In a skillet carefully place baguette slices with cheese side down and cook for 3 minutes or until cheese is golden brown around the edges. Turn and cook 30 seconds more. (Cook in batches if necessary.)
Toss tomato slices with oil, lime juice, cilantro and garlic salt. Marinate for 5 minutes.
In a small bowl mash avocado and drizzle with half the tomato marinade.
Spread equal amounts of mashed marinated avocado onto bread slices. Top with tomatoes and walnuts. Sprinkle with additional cilantro, if desired.