I have been saving all the beef fat trimmings for quite some time. Basically I rendered down all the fat with a lot of rosemary, thyme, garlic, and bay leaf in a roasting pan. After a few hours in the oven, the fat was rendered. I strained it and allowed it to cool to room temperature. I froze the mixing bowl to our Hobart mixer and then whipped the fat to create a butter consistency.
When serving the beef fat it should be close to room temperature or it won't be as spreadable. I have been using it for everything, starting with our charcuterie board. Rich fried an egg with it, which I thought was pretty clever (steak & eggs). The picture above is whipped beef fat / picholine and fennel tapenade / orange peel.