In a small bowl, mix the mayonnaise, horseradish and dried basil. Set aside.
If you are using sliced bread, you can toast the bread to make it a little more sturdy. In hindsight, I should have done this because the bread mix I wanted to use baked up more like cornbread. It was good bread on its own, but not good for sandwich bread. The picture on the box was misleading as it showed a loaf of artisan-type loaf that I thought I could slice, which was not the case at all. I think sliced bread would work much better.
Cut the loaf in quarters to result in four pieces. Then, slice each quarter through the middle to make a top and bottom piece.
Before building the sandwich, gather all the components in one place for easier assembly.
To build the sandwich: Lay out the bread side-by-side. Spread some of the mayo on each slice of bread. Next place a slice of cheddar cheese on one slice of the bread and the provolone on the other. Split the cheese slices in half to fit on the bread if needed.
On one slice, place the lettuce, tomato and boiled egg slices.
On the other slice, place the bacon, ham, turkey and avocado.
Finish with the lettuce and bacon.