That's all he really wanted. He came there wanting cake, and that's what he got. The note said cake. It didn't say:
"Dear Mario, please come to the castle. I've decided to marry you."
No, it said:
"Dear Mario, please come to the castle. I've baked a cake for you."
If she was going to marry a 40 year old plumber, she would've said so in the letter.