1. Preheat oven to 350 degrees, line baking sheet with foil and nonstick cooking spray.
2. Combine sugar and 1 tablespoon vinegar in small saucepan and cook until the sugar is dissolved. Add walnuts, coat and spread on baking sheet. Bake 10 minutes until walnuts are golden brown, stirring halfway. Set aside to cool.
3. Whisk together remaining vinegar, oil, and shallots in large bowl. Lay bread slices on baking sheet and broil for 3 minutes on each side or until lightly toasted. Top bread with cheese slices and broil for about 2 minutes until the cheese is warm.
4. Toss apple slices and arugula in bowl with dressing and season with salt and pepper. Finish with walnuts. Serve with cheese toast.
Get more of Cristina's fabulous recipes here: www.cristinaferrarecooks.com.