This is so simple–I almost shouldn't call it a recipe.
Slice a loaf of ciabatta bread in half lengthwise.
Spread with your favorite pesto sauce (I've used traditional basil pesto and sundried tomato with equal success)…make it fresh or buy premade.
Top with sliced fresh mozzarella.
Bake in 375 degree oven until the cheese melts.
Add sliced tomatoes (optional).