"¿Qué les encanta comer?"
Translation:What do they love to eat?
Because it's a reflexive verb, another colloquial translation is "What do they enjoy eating?" This gives a clue that if it were English grammar—and it is not!—then "comer/eating" would be the subject, "is" would be the predicate verb, and the phrase "what they enjoy" would be the DO.
Going for the Spanish translation, it IS "love" in English, but I agree that the grammar doesn't make sense.