The Lion, the Witch and the Wardrobe
Why it's similar
C.S. Lewis and Tolkien were friends, fellow Oxford professors, and members of the Inklings literary group. They read each other's work in progress and shared a conviction that myth and fairy tale were not lesser forms of literature. The Lion, the Witch and the Wardrobe channels that shared belief into a story about four children who step through a wardrobe into a frozen kingdom ruled by a tyrant queen. The Narnia books are shorter and faster than The Hobbit, but they carry the same sense of ancient magic pressing through into the everyday.
Both authors write worlds where good and evil are real forces, not abstractions. Bilbo faces Smaug. The Pevensie children face the White Witch. In both cases, the heroes are ordinary people who discover courage they did not know they had. Lewis's prose is plainer than Tolkien's, more direct and less lyrical, but it moves with a confidence that keeps you turning pages. If you grew up with one of these books, you owe it to yourself to read the other.