Marcelino Pan y Vino, by Jose Maria Sanchez-Silva.
Marcelino is an orphan who was abandoned as a baby at the doorstep of a small Franciscan monastery. He grows up to be a mischievious little boy who has the run of the monastery. He only place he’s not allowed to visit is the attic. Of course, he sneaks up there, anyway. In the back room, he finds a life-size crucifix. Marcelino offers the Jesus statue some bread. Marcelino returns to visit whenever he can, always with bread and wine.
This 1953 book has become a classic of Spanish children’s literature (and, in 1955, of Spanish film).