Slice baguettes in half and then lengthwise but don't cut all the way through.
Slather the bottom half of the baguettes with pesto. Top with prosciutto, tomatoes and mozzarella. Drizzle with olive oil and season with salt and pepper. Placing the mozzarella on top will keep the top of bread from getting soggy from tomatoes.
Wrap sandwiches tightly in parchment and slice in half. Pack away.
Place walnuts, cheese, garlic, and 1/2 cup olive oil in a blender and puree until smooth. Add basil and parsley, and then with the motor running, gradually add the remaining olive oil until pesto is thick and smooth. Season with salt and pepper, to taste.