[pliny]

If you want to make a PB&B that uses the entire banana, simply peel the banana, coat the flesh in PB, tear up your bread slices and adhere them to the banana.

This method is not guaranteed to use all the bread.

[vermarish]

This method may also compromise the structural integrity of the banana after trying to spread PB on it.

[jholman]

I agree, pliny hasn't thought it through.

Smear peanut butter on the bread, NOW tear up the bread, and apply the peanut-butter-smeared shreds to the (peeled) banana.

Still the same primary advantage as pliny's method, same primary drawback (may not exhaust the bread), but we've solved the structure problem that you raise.

I feel the trend-line here is looking good; with a few more iterations, we may reach the true ideal PB&B sandwich.