One who eats peanuts recites before eating the Beracha of "Boreh Peri Ha’adama." Peanuts differ in this regard from all other nuts. All nuts require the Beracha of "Boreh Peri Ha’etz," with the exception of peanuts, which require "Boreh Peri Ha’adama."
What Beracha does one recite over a peanut that has a covering made from flour? Do we determine the Beracha based upon the covering, in which case one must recite "Mezonot," or based upon the peanut, in which case one must recite "Boreh Peri Ha’adama"?
The Gemara in Masechet Berachot establishes the rule that if a food contains flour, the flour is considered the primary ingredient and one therefore recites the Beracha of "Mezonot." Even if a person is more interested in the other part of the food than the flour, nevertheless, so long as the flour was added for flavor, it is viewed as the main ingredient. Therefore, one who eats a covered peanut first recites the Beracha of "Mezonot," even if he is more interested in the nut than in the covering.
What Beracha Aharona would one recite after eating covered peanuts?
If one ate enough peanuts that the dough coverings he ate amount to a total of 30 grams, the he recites the Beracha of "Al Ha’mihya." If he did not eat this quantity of covered peanuts, but he ate enough that the nuts themselves amount to 30 grams, then he must recite the Beracha of "Boreh Nefashot."
This is the position of Rabbi Moshe Halevi (Israel, 1961-2001), in his work Birkat Hashem (vol. 3, p. 337). It should be noted that Hacham Ovadia Yosef, in his work Yalkut Yosef (vol. 3), adopts a different view.
Summary: If one eats peanuts covered with a covering made from dough, he recites the Beracha of "Mezonot." If he ate enough that the peanuts he consumed contained 30 grams of dough covering, then he recites after eating the Beracha of "Al Ha’mihya." If he did not eat this amount but he did eat an amount consisting of 30 grams of nuts, then he recites "Boreh Nefashot."