Prepare cornbread according to package directions; cool and crumble. Set aside.
Stir together dressing, mayonnaise, and buttermilk until blended.
Layer crumbled cornbread, shredded lettuce, and next 7 ingredients evenly into 6 (3- to 4-cup) glass containers; spoon half of dressing mixture evenly over tops. Cover and chill at least 3 hours or up to 24 hours. Sprinkle with green onions just before serving. Serve with remaining half of dressing mixture on the side.
Note: For testing purposes only, we used Martha White Buttermilk Cornbread Mix and Girard's Parmesan-Peppercorn Dressing. We used 3-cup marquis-shaped canning jars with lid and screw ring. To find a retailer, visit www.leifheitusa.com, or call toll-free 1-866-695-3434.
To make 1 large salad: Layer half each of crumbled cornbread, shredded lettuce, and next 7 ingredients in a large glass bowl; spoon half of dressing mixture evenly over top. Repeat layers ending with dressing mixture. Cover and chill at least 8 hours or up to 24 hours. Sprinkle top with green onions just before serving. Prep: 45 min., Chill: 8 hrs.
Layered Southwest Cornbread-and-Turkey Salad: Substitute 1 (6-ounce) package Mexican cornbread mix for 1 (6-ounce) package buttermilk cornbread mix; 1 (16-ounce) bottle buttermilk-Ranch dressing for Parmesan-peppercorn dressing; 1 (8-ounce) package finely shredded Cheddar and Monterey Jack cheeses with jalapeño peppers for shredded Swiss cheese; and 1 (11-ounce) can sweet whole kernel corn, drained, and 1 (15-ounce) can black beans, rinsed and drained, for yellow bell peppers. Prepare recipe as directed, omitting mayonnaise.
Note: For testing purposes only, we used Gladiola Mexican style cornbread mix and Ken's Steak House Buttermilk Ranch dressing.