See also the The Laws of Berachos, pg. Preferably, steamed grain should be eaten only during a meal to avoid making a questionable berachah 40. See also Vesain Berachah, pg. In reality, there are many ways to produce granola and each company does it differently. Methods are constantly changing.
Recent research shows that the bran and part of the endosperm is removed during the puffing process.
Puffing is not cooking, since no water is used. Some Rishonim hold that mezonos can be recited only if the kernels adhere to one another. See The Laws of Berachos, pg. Mekor ha-Berachah 54. See, however, Kol ha-Torah, vol.