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So I bought an E3d all metal hotend a couple months ago, and it was running great until I somehow had it ooze PLA everywhere. Just...everywhere. The entire heater block, nozzle, and heatbreak were covered in PLA. However! Since the whole thing is metal, no PEEK or teflon in sight, I took as much of it apart as I could and tossed it into my oven on a sheet of foil, and set the oven to self clean.

Self clean runs at 500c.

Long story short, I'll need a new heater core, but what was solid PLA gumming up everything in the hotend is now a layer of fine ash, which I'll be rinsing away.

NOTE: This did make my apartment smell like burning plastic for an hour, I had to open all of my windows.

That was a great idea! Despite the smell, I can't think of an easier way to clean a mess like that.
Do you have any idea how the PLA ended up all over everything?

I've had this happen, it only happens when you don't have the nozzle and the heat break threaded in tight against each other. don't put too much torque on them to break the heat break, but you need them to be firmly meshed together or else the PLA will leak through the gaps and climb up and down the threads.

There's an easier way to do this if your stove is capable of it.

If your burners have a removable metal cap on top that spreads the gas out to the edges from a central pipe, removing the metal cap when the burner is lit (preferably on Low) will expose a jet of flame. You'd want to do this very carefully, of course. If the gas flow is too high it will blow out its own flame! With mine, I can blowtorch all the gunk off a heater block or nozzle in a few minutes. With the hood fan turned on, all the stink molecules go outside.

Caveat: Can't do this with aluminum nozzles (because they'll deform and possibly crumble), but unless you're using a Budaschnozzle it's not an issue.

If my stove didn't have this feature I'd go to a hardware store and buy a brazing torch, like plumbers use. It's very efficient!