Begin by filling a large pot with water and bringing it to a rolling boil over high heat. Once boiling, generously salt the water and add the tri-color rotini pasta. Cook for about 8-10 minutes, or until the pasta is al dente. Drain the pasta in a colander and cool it off under cold running water.

In a large mixing bowl, combine the cooled tri-color rotini with the vibrant cherry tomatoes, sliced pepperoni, diced red onion, and chopped green bell pepper. Toss in the creamy mozzarella cheese and grated Parmesan. Gently stir until well integrated.

In a separate bowl, whisk together olive oil and red wine vinegar. Add Italian seasoning, garlic powder, salt, pepper, and red pepper flakes. This zesty vinaigrette will elevate your pasta salad.

Pour the vinaigrette over the pasta salad mix and toss gently until all components are evenly coated. Cover the bowl and refrigerate for at least one hour.

Prior to serving, remove the salad from the refrigerator and allow it to sit at room temperature for 20-30 minutes. Give it another gentle toss before serving.