blending

Do you mean to appear with sharp corners? You will need some retouching using Clone Stamp tool, for example.

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I am trying to figure out how to make the edges on the cookies blend or wrap around the sqaure to make appear like the cookies are square. 

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I am not sure what you mean exactly, the cookies seem to look pretty square already. 

To edit shapes in general there options, ideally as Smart Filters naturally.

Filter > Liquify or Edit > Puppet Warp for example. 

Hi one of simple way is use rectangular marquee tool and copy on cookies in square holding shift and then paste to make square copy or version...regards