Sugar and Spice by Sarah Mlynowski
Whatever After continues
Playing with the golden ball from The Frog Prince breaks a lamp, and Abby and Jonah are in trouble.
And then they go through the mirror in a land with many vegetable gardens with no one allowed in. They meet up with Hansel and Gretel who look exactly like them.
It involves eating vegetables, licorice, a worried father, and more.