Bring a large pot of salted water to a boil and cook the penne according to the package directions until al dente.
Drain the pasta and rinse it under cold water to stop the cooking process. Set aside to cool completely.
In a small bowl, whisk together the orange juice, olive oil, honey, Dijon mustard, salt, and black pepper until smooth.
In a large serving bowl, combine the cooled pasta, feta cheese, dried cranberries, toasted walnuts, baby spinach, and sliced red onion.
Pour the dressing over the salad and gently toss until everything is evenly coated.
Refrigerate for 15–20 minutes before serving for the best flavor. This Feta Cranberry Penne Salad tastes even better after the ingredients have had time to blend together.