Caught two Brook/Splake (can't really tell the difference) on our recent September trip.
First one was quite large so I gutted it (cut/scrape out the blood line or it will taste fishy), then cut into steaks about 1/2-3/4" thick and pan fried it in olive oil with salt and pepper. Fillet near the tail when it gets too small to cut into steaks.
Second one was smaller (~13"). I gutted it, removed the head, then rubbed with oil and salt/pepper and cooked on a grate over the fire. The best part of this method is that all the bones pull right out when done. This is the easiest method by far, but hard to penetrate with seasoning if that's what you're in to. Still tastes great, just different than pan fried, more like baked I suppose. You can stuff the cavity with garlic/lemon/etc. if you have it with you.
Cleaning like that is much easier than trying to fillet in my opinion. I'm not great at filleting (especially trout) so this works out well for me since it's really hard to mess up and has virtually zero waste. Since there are no scales, I just leave the skin on. When cutting the head, don't cut all the way down and you can pull everything out together with your thumb for easy disposal.