Making gravy without drippings or butter? Long story short: I made a bunch of meatloaf and I forgot to buy butter. I need to make gravy.

The way I usually make gravy is to melt some butter, to supplement whatever drippings I have, make a roux and add some broth – chicken or beef, depending on what the gravy is to be served with – to get to the desired viscosity.

But I forgot to buy enough butter. Can I use olive oil? Is there another way to make gravy from scratch without drippings?
You can make a roux with any fat.  Olive oil will certainly work.  There are also other methods for thickening a gravy, such as the addition of cornstarch or arrowroot.