Step 1

In a large pot, bring 4 quarts water and 1 tablespoon salt to boil. Add pasta and cook according to package directions for al dente (usually 8 to 12 minutes depending on the exact noodle). Drain well and rinse with cold water.

Step 2

Meanwhile, bring 2 quarts water and 1 teaspoon salt to boil. Fill a medium bowl with cold water and ice. Add the broccoli and blanch until bright green and tender-crisp, about 3 minutes. Transfer to the ice water to stop the cooking, then drain well.

Step 3

In a large bowl, whisk together mayonnaise, Italian dressing, and Parmesan cheese. Stir in pasta, tomatoes, bell pepper, and scallions. Carefully fold in crab and stir until evenly coated. Cover and chill until serving time.