Is it safe to eat butter that have mold on the surface? I have got a large chunk of butter, with some green molds growing on one surface only, with spots that are 1cm in diameter, and only like 3~4 of them total.

the butter itself tastes and smells fine, once i cut off the mold parts.

it is unsalted butter.

It has been sitting in the fridge for few weaks.

so is it safe to eat butter after completely removing the mold parts ?
You could theoretically salvage the butter, but it really boils down to mold type. Melting and filtrating the butter will get rid of the mold and create ghee. But filtration will not remove aflatoxins that some types of molds produce.