Preheat an outdoor grill for medium-low heat and lightly oil the grate. Place focaccia on a work surface and spread pesto on top. Layer tomatoes over the pesto and sprinkle with Italian cheese blend. Place focaccia on grill and cook until cheese is completely melted and tomatoes are warmed through, 5 to 10 minutes. Watch the bottom for burning and move to higher rack if necessary. Slice bread into 1-inch strips and enjoy.