えにかいたもち
pie in the sky; castles in the air; drawing of a rice cake
Also written 絵に描いた餠、絵にかいた餅
Expression
君きみの夢ゆめ一杯いっぱいのビジネスプラン、絵えに描かいた餅もちにならんことを切せつに望のぞむよ。
This business plan of yours seems almost too optimistic. All I can say is I hope it's more than just wishful thinking.