
So you've melted some butter and added it to your dough, as planned.

But in the now empty container where you melted the butter (saucepan, bowl or other), there's still a little left, at the bottom and around the edges.

The trick is to use this little leftover, to brush it off, at the bottom and around the edges...

... and simply use it to butter your mold.
That way you don't waste anything, and you've already got melted butter to easily butter your mold.