The Frog Princess by E D Baker

Princess Emerelda is not exactly an ideal princess. Her laugh sounds like a donkey's bray rather than tinkiling bells, she trips over her feet more often than she gracefully curtsies, and she hates the young Prince Jorge who her mother sees as a potential son-in-law! But if Emma (as she likes to be known) ever thought to escape from her frustrating life, she never expected it to happen by kissing a frog!