Ingredients

• 2 tablespoons coarsely chopped walnuts
• 1/4 cup extra-virgin olive oil
• 1/4 cup (1 1/2 ounces) grated Parmesan cheese
• 1 garlic clove
• 2 cups (lightly packed) fresh basil leaves (about 3 1/2 ounces)
• 8 1/3- to 1/2-inch-thick slices country-style white bread
• Olive oil (for brushing)
• Citrus Tapenade
• 6 ounces thinly sliced prosciutto
• 8 ounces fresh mozzarella cheese, cut into 1/4-inch-thick slices
• 4 tablespoons aged balsamic vinegar

Instructions

1. Toast walnuts in small skillet over medium heat until golden brown, stirring often. Cool. Puree walnuts, olive oil, Parmesan cheese, and garlic in processor to paste, stopping occasionally to scrape down sides of bowl. Add half of basil leaves; puree. Add remaining basil; blend until coarse puree forms. Season pesto to taste with salt and pepper.
2. For sandwiches: Brush 1 side of each bread slice with olive oil. Heat griddle or heavy large skillet over medium-high heat; grill bread, oiled side down, until golden brown, about 1 minute. Transfer grilled bread to clean work surface; let stand until cool. Turn 4 bread slices over (grilled side down) and spread thin layer of Citrus Tapenade evenly over each. Top with prosciutto slices, then mozzarella cheese slices. Drizzle with pesto. Drizzle 1 tablespoon balsamic vinegar over ungrilled side of each of 4 remaining bread slices. Place bread, grilled side up, atop sandwich filling. Cut sandwiches in half and serve.
3. Brush 1 side of each bread slice with olive oil. Heat griddle or heavy large skillet over medium-high heat; grill bread, oiled side down, until golden brown, about 1 minute. Transfer grilled bread to clean work surface; let stand until cool. Turn 4 bread slices over (grilled side down) and spread thin layer of Citrus Tapenade evenly over each. Top with prosciutto slices, then mozzarella cheese slices. Drizzle with pesto. Drizzle 1 tablespoon balsamic vinegar over ungrilled side of each of 4 remaining bread slices. Place bread, grilled side up, atop sandwich filling. Cut sandwiches in half and serve.