1. Line a baking sheet with parchment paper and lightly oil. You do not need to use all of the oil, just use enough for a VERY light coating - the more oil used, the more soggy the crutons will be and the more cooking time you will need to get them browned.
2. Take the pre-cooked polenta out of the package and, on a cutting board, cut into about 1 inch cubes.
You can find pre-cooked polenta at most grocery stores, looks something like this: