In a blender or food processor, puree the basil leaves, olive oil and garlic.
Mix in the pine nuts and Parmesan cheese. Continue processing until desired consistency is reached.
Preheat the broiler.
Slice Italian bread to desired thickness.
Spread a layer of pesto on each slice. Top with roma (plum) tomatoes and mozzarella cheese.
Place topped bread slices in a single layer on a large baking sheet. Broil 5 minutes, or until cheese is bubbly and lightly browned.