Slice mozzarella cheese into 1/4" slices then cut into but 1" squares and set aside
Brush both sides of bread with olive oil and crisp up by placing on a hot grill (watch and turn so they don't burn - you just want to get some grill marks on both side) then cut into about 1 1/4" squares and set aside
To make pesto, place basil and pine nuts in a food processor and process until chopped fine
Add romano cheese, garlic and cheese and process until mixed
With blade running, drizzle olive oil slowly until it is incorporated.
If desired, add salt and pepper to taste
To assemble, place about a 1/2 teaspoon of pesto on bread, top with mozzarella, cherry tomato and secure with toothpick