Pulse all the ingredients (except for the water) together in a food processor or blender.
Add the cold water to the dough, a bit at a time, until the mixture is holding together well enough to work into a ball or two.
Separate into two balls of dough, and place each ball on a Silpat, parchment paper, or other non-stick surface (which you will transfer to a baking sheet). You can roll it all on one sheet, but I find it easy to do it on two sheets. And two sheets bake more evenly.
Roll each dough ball out until flat and about 1/8 to 1/4 inch in thickness.
Using a pizza cutter or knife, score the dough into squares, so you have squares that are the size of croutons (the size you like, that is).
Bake for 25 minutes, or until croutons are browned. The darker, the crunchier.