In large pot of water, boil elbow noodles until al dente according to package directions. Drain water.
In large skillet, melt butter over medium heat. Once melted, whisk in flour. Stir until golden-brown. Slowly whisk in milk. Turn heat to medium-high and continue to stir until mixture comes to boil. Reduce heat to low and stir in mozzarella cheese. Stir constantly until cheese has melted.
Stir in cooked elbow noodles to cheese mixture. Remove from heat.
In small bowl, combine diced tomato, balsamic vinegar and garlic. Stir.
Top each macaroni and cheese serving with 1 tablespoon bread crumbs and 2 tablespoons tomato mixture.