If a person eats cereal with milk, which Beracha or Berachot does he recite? If, for example, the Beracha over the cereal itself is Mezonot, as is often the case, does the person recite only Mezonot, only She'hakol (the Beracha over milk), or both?
The Gemara in Berachot establishes that when a person eats two foods together, he recites a Beracha over only the primary food, and this Beracha covers the secondary food, as well. Even though the secondary food independently would require a different Beracha, when it is subordinate to a primary food the Beracha over the primary food covers this secondary food, as well.
Our question thus becomes, do we consider the milk subordinate to the cereal, or is the cereal deemed subordinate to the milk?
Rabbi Moshe Feinstein (Russia-New York, 1895-1986) addresses this question in his work Iggerot Moshe (2:43), and he concludes that the milk is to be viewed as subordinate to the cereal. Since the milk serves to soften the cereal and make it easier to chew and swallow, as well as to enhance the cereal's taste, it clearly plays a secondary role. Therefore, one who eats a grain cereal with milk recites only the Beracha of Mezonot, which covers both the cereal and the milk.
Rabbi Feinstein adds that even if some milk remains after one has eaten all the cereal, and he now wishes to drink the remaining milk, he does not recite She'hakol over the milk. Since the milk had been together with, and subordinate to, the cereal, it was covered by the Beracha recited over the cereal, and therefore it does not require its own Beracha. Similarly, if a person eats apple pie, he recites only the Beracha of Mezonot, which covers both the crust the primary component of the pie and the apples. And even if one completes the crust and now eats only apple, he does not recite a Beracha over the apple, because it had been covered by the Beracha of Mezonot recited initially over the crust.
Rabbi Feinstein notes one exception to his ruling concerning the Beracha recited over cereal and milk. If a person adds a significant amount of milk to his cereal for medical purposes, such as to increase his daily calcium intake, then the milk now serves a function other than simply enhancing the texture or taste of the cereal, and as such, it requires a separate Beracha. In such a case, therefore, one would recite Mezonot over the cereal and She'hakol over the milk. If a parent adds milk to a child's cereal for health purposes, but the child perceives the milk simply as enhancing the cereal, without any interest in the health benefits, then the child would not recite She'hakol over the milk, since from his perspective the milk is added to enhance the cereal's taste, and not for any intrinsic purpose.
If a person adds bananas, raisins, or other fruits to his cereal and milk, does he recite a separate Beracha over the fruit, or does the Mezonot recited over the cereal cover the fruit, as well?
Once again, we follow the principle that the Beracha recited over the primary food covers all other foods partaken of together with that food. In this case, then, since the fruit is subordinate to the cereal, the Mezonot recited over the cereal covers even the fruit.
It should be noted, however, that if a person decided to add the fruit only after he recited the Beracha of Mezonot, then he must recite a separate Beracha over the fruit. Since he did not intend when he recited Mezonot that this Beracha should apply to the fruit, when he adds the fruit he must recite a separate Beracha. However, if a person regularly adds fruit to his cereal and milk, then we assume that he had the fruit in mind when he recited the Mezonot, and thus even if he added the fruit only after reciting Mezonot he need not recite a separate Beracha over the fruit.
Summary: One who eats cereal with milk recites a Beracha over the cereal, and this Beracha covers the milk, as well, including leftover milk that one drinks after finishing the cereal. An exception is a person who adds milk for strictly health purposes, who must recite a separate Beracha of She'hakol over the milk after reciting the Beracha over the cereal. The Beracha recited over cereal also covers fruits that one adds to his cereal, assuming he had those fruits in mind when he recited the Beracha. If one added the fruit only after reciting the Beracha and he does not ordinarily add fruit, then he must recite a separate Beracha over the fruit.