I was hoping for an answer, but I'll tell you what I do because hot water and soap rarely do the trick.

I know it's a toaster oven, but this what I do for my main oven and it usually works pretty well.

I take a baking pan (3 inches deep) (metal works best) and fill all the way up to the top with water, put in about 2 T of dish washing liquid with grease cutter, and lots of real lemon juice and stir.

I set the oven to 250 degrees celsius and slide the dish into the oven and leave it inside the oven until nearly all of the water has evaporated off.

The using a silicone heat proof oven mitt I start with a good thick sponge to work on cleaning the door because it's coolest and the heat inside the oven will keep the grease loose until you work your way inside.

If you have a lot of grease it may take awhile and you have to repeat the steps, but it seems to work well for most grease and other stains. It just takes a long time!

By the way, the same process works with a bowl in the microwave!

1) Unplug your toaster oven,
2) remove all removable acessories,
3) spray with a 60% vinegar 40% hot water solution,
4) wait about 5 minutes,
5) scrub rinsing your sponge out under hot water in the sink frequently.

OR

If desperate, use oven cleaner - but beware that it may damage the interior "coating."

Some of the discoloration may remain but most of the fat should be removable. I like to line the bottom (underneath the heating elements) of my toaster oven with tin foil which I can regularly and easily change. You might consider also using a little tin-foil-tent to minimize the splatters.

I own the breville model pictured in this article and rarely need to clean it other than the occassional magic eraser wipe and emptying out the crumbs.

If you're making bacon in it, use the included tray and place one piece of foil on it, lay down the bacon, and place a second piece of foil on top of it to prevent splatter.

If bacon's the main reason for cleaning, it's easier to prevent the issue rather than dealing with it periodically.

I just scrub mine with an SOS pad, everything comes clean minus a few stains. Including the glass. Have been doing it for a loooooong time, no scratches or anything.

I've tried many things and they don't work. When you have grease splatter that's been literally baked on for months/years, nothing is getting it off. The best solution is to clean up messes ASAP. Otherwise, each time you toast you bagel, you are embedding it deeper.

Mr. Clean Magic Eraser does wonders for my toaster oven.

I'd put on a pair of gloves and go after it with a wet rag and some borax.

Whenever I have to clean up any grease/oil, I use a damp cloth or sponge and baking soda. I'm always amazed at what it'll clean that other cleaners can't. I use it regularly to clean my metal tea kettle that always get splattered with oil. It's great to clean kitchen cabinets, counter tops and refrigerators too.

A little baking soda? I don't know :( I'm faced with the same problem myself though.

I'd follow the other advice for the inside, but for the glass door: A razor blade. Much like on a glass stove top, a razor blade works WONDERS on grease baked into the glass. Use glass stove top cleaner if you like, but a little soapy water and razor blade works just as well.

Soap and water works great on the inside. I use The Natchez Solution to clean my kitchen cabinets. It is all-natural. Just lemon oil and beeswax with some mineral...a little on a soft cloth and grease comes loose without disturbing your finish,,,works on painted cabinets or varnished wood. I finish of my cleaned stainless steel appliance too. I got it on Amazon but it is available on their web site too.