Prepare the ingredients: chop the garlic and slice the mozzarella cheese.
Heat the olive oil in a saucepan over medium-high heat. Once the oil is hot, add the garlic and cook for a minute or two until it begins to soften.
Reduce the heat to medium-low and stir in the balsamic vinegar. Cook for a few minutes and stir in the tomatoes and basil. Simmer over low heat for 10 to 15 minutes.
Transfer the sauce to an ovenproof dish and arrange the mozzarella slices on top of the sauce.
Place the sauce with cheese under a broiler for a few minutes until the cheese melts.
Notes
Make Ahead Instructions:Make the sauce and store it in the refrigerator for up to 3 days.About 30 minutes before serving, remove the sauce from the refrigerator. Once it's at room temperature, place it in a preheated 375 degrees f oven for 8 to 10 minutes until it is heated through. Remove it and place the cheese on top.Place it under a broiler (low to medium heat) and cook until the cheese has melted.Store leftovers in the refrigerator for up to 5 days in an airtight container.See article above for variations, tips and more!