Bring a large pot of salted water to a boil. Cook the penne according to package directions until al dente.
Drain the pasta and rinse under cold water until completely cool. Drain well.
In a small bowl, whisk together the orange juice, olive oil, honey, Dijon mustard, salt, and black pepper until smooth.
In a large mixing bowl, combine the cooled pasta, feta cheese, dried cranberries, toasted walnuts, baby spinach, and sliced red onion.
Pour the dressing over the salad.
Toss gently until everything is evenly coated.
Chill for 15–30 minutes before serving for the best flavor. This Feta Cranberry Penne Salad tastes even better after the ingredients have had time to absorb the citrus dressing.