Squeeze excess moisture from thawed artichokes and cut into half. Place on a parchment lined sheet tray, in a single layer. Drizzle artichoke with olive oil and season with salt and pepper to taste. Roast at 400 degrees for 30-35 minutes, until brown and caramelized.
While artichokes are roasting, make the dressing.
In a large bowl, add roasted artichokes, hearts of palm, grape tomatoes, capers and toasted walnuts. Drizzle with 1/4 cup of the dressing and gently toss to combine.
Place romaine hearts on a large platter or divide among six salad plates. Top with the dressed vegetable mixture and sprinkle with parmesan cheese. Serve the remaining dressing on the side.