This relatively easy and elegant butterfly is made from a base I have called big
squash. The are two variations of the big squash, this one begins with a squash
similar to that used on the bird base. The second variation big squash base
uses a squash that could be used to form a petal on a on a bomb base. The big
squash is the fold that follows a single bird or bomb base squash

Big Squash Butterfly