Bring a large pot of water to a rapid boil. Generously salt the water with 1-2 tablespoons kosher salt. Add the pasta and cook according to package directions until just al dente. Drain but DO NOT rinse.
While the pasta cooks, prepare the dressing. In a small bowl or jar, combine ⅓ cup balsamic vinegar, ¼ cup extra virgin olive oil, ½ teaspoon minced garlic, ½ teaspoon kosher salt, ¼ teaspoon pepper, ½ teaspoon onion powder, ½ tablespoon Dijon mustard, and 1 tablespoon molasses. Whisk or shake until well combined and emulsified.
Drain the pasta well, but do not rinse. Transfer the warm pasta to a large mixing bowl and toss with half of the prepared dressing. Allow the pasta to cool for 10-20 minutes, until just slightly warm or at room temperature. Speed up the process by spreading the noodles out onto a rimmed sheet pan.
Once the pasta has cooled, return it to the mixing bowl if needed. Add the remaining dressing, tomatoes, mozzarella, and basil. Toss gently to combine.
Cover and refrigerate the pasta salad for at least 30 minutes before serving. Once chilled, toss again and serve.
Notes
Basil: To chiffonade basil, stack the leaves, roll them tightly, and slice into thin ribbons.Tomatoes: If using Roma or vine-ripened tomatoes, remove the seeds before chopping to keep the pasta salad from becoming watery.Storage: Store in an airtight container for up to 3 days in the refrigerator.Refreshing Leftovers: Pasta absorbs dressing as it sits. If the salad seems dry after chilling, toss with an extra ½ tablespoon olive oil and ½ tablespoon balsamic vinegar before serving again.