Bring a large pot of salted water to a boil. Add the small shell pasta and cook until al dente, usually around 8-10 minutes. Drain and rinse under cold water.

In a large mixing bowl, combine the drained whole kernel corn, well-drained Rotel, and chopped green onions. Stir gently.

In a separate bowl, whisk together mayonnaise and sour cream until smooth.

Pour the dressing over the corn mixture and stir to combine. Gently fold in shredded cheddar cheese.

Carefully add the cooled pasta to the salad mixture, folding it in gently.

Cover and refrigerate for at least 1-2 hours before serving.