Cook the orzo pasta according to package instructions until al dente. Drain and rinse under cold water to cool.
In a large bowl, combine the cooled orzo, prosciutto, cherry tomatoes, spinach, and Parmesan cheese.
In a small bowl, whisk together the olive oil, red wine vinegar, Dijon mustard, minced garlic, salt, and pepper until well combined.
Pour the vinaigrette over the orzo salad and toss gently to combine all ingredients.
Taste and adjust seasoning if necessary. Serve immediately or chill in the refrigerator for about 30 minutes to allow flavors to meld.