Start at the bottom of The Other Drop. Plant a Rainbow Potion between the vendor and the pointy grey rock. Jump left to reach a ledge. Then it's four spinach jumps straight up, and you're at the top exit!
I had this idea weeks ago, but then my internets broke, and Christmas happened, and today was the first chance I had to test my theory. If someone else already pointed this out, then I apologize. I'll just be over here, doing my mad scientist happy dance.