For the avocado chicken layer: Add the buttermilk, lime juice and avocados to a bowl. Mash the avocado until everything is combined. Fold in the chicken, bacon, chives and scallions. Season with salt and set aside.
For the pimento cheese layer: Add the Cheddar, mayonnaise and pimento to a bowl and stir to thoroughly combine. Set aside.
For the ham salad layer: Add the ham, mayonnaise, Dijon mustard, pickles, celery, scallions, onion, jalapeno and some salt and pepper to a bowl. Stir to combine and set aside.
For the ranch frosting: In the bowl of a stand mixer fitted with a paddle attachment, or using an electric hand mixer, mix the cream cheese until the cubes have combined. Add the buttermilk, white wine vinegar, garlic and grated onion and stir to combine.
To assemble: Add desired layers between each bread layer. Spread a crumb coat of the ranch frosting to seal the cake, then add another layer of frosting to cover the cake. Decorate as desired with various toppings.