Keep the editor as a single window application

There is no option I am aware of to keep the editor as a single window application. You end up with ,multiple windows open on  the desktop which quickly gets confusing if you have more than one instance of UE running with multiple projects open.

And the first thing I do when opening a project is to drag all the tabbed asset editors to the main application window. Anyone know of a way to make the editor default to a singe window at all times?

I don’t know how many projects you are working with, but generally if you drag all your tabs into the main window (including stuff like message log, find window) and then restart the editor, new blueprint tabs will stay on the main window, and other windows that were placed there before will return to it when they reopen.
There’s probably a way to hack your configuration to make this default behavior, might be worth looking through some ini files in Engine/Config folder if it really bothers you

That doesn’t seem to be the case. My assets are always reopened in a separate window.