What l’maseh is the bracha to be made on “croutons”?
The berachah for croutons is usually mezonos.
However, this depends on how the croutons (not soup-nuts, which are always mezonos) are made.
Some are baked, some are baked twice and others are baked and then fried.
If the croutons are immediately baked to a level of crispiness (one of the possibilities of pas haba be-kisnin), the berachah will be mezonos.
Similarly, if the bread was baked into normal bread, and then diced up to pieces smaller than a kezayis and then fried, it would be mezonos (we can assume that the frying, in the case of croutons, is similar to cooking and not to baking; for regular frying, see Shulchan Aruch, Orach Chaim168:10; Mishna Brurah 52, 56).
If the croutons are baked into normal bread, and then diced up into pieces smaller than a kezayis, and then baked again into crispy croutons, their formal berachah is hamotzei. However, many rule that because the initial intention was to make them into a crouton snack, intermediate step of normal bread is overlooked.
Thus, one can generally assume that the berachah for croutons is mezonos (as ruled by Veten Bracha Handbook p. 36; Vezos Habracha p. 122), though some are stringent and are careful to eat them only as part of a meal.