The sauce can be faked with water and food coloring (a bit of caramel coloring would be easiest, as opposed to trying to make a suitably dark brown with the standard food colorings in the red, yellow, blue, green veins). The egg is going to be a lot harder to fake. The easiest way to do it, if your actors are hesitant to swallow a raw egg, is to use ceramic mug that can't be seen through. That way the actors can "drink" it without having to swallow it.