The way I prepare fly agaric, is to upend the caps (red side down) on foil lined baking trays, and heat overnight until crispy dry at the very lowest heat setting the oven is capable of maintaining.
Baste every so often with the juices that sweat out under the heat. I tend to scrape the gills off and discard as they contain a whole load of water, and will make drying without turning into a blob of nasty mush much easier to accomplish.
I take mine as tea, usually, sweetened with a bit of sugar (no milk, that would be revolting in fly agaric tea IMO) and get good results. An amazingly versatile mushroom, good as an endurance boosting tonic in lower doses, pain reliever, sleep aid, psychedelic, and it makes a wonderful spice for cooking meat dishes, I think of it as nature's own MSG in that respect
The curing treatment is essential though, fresh, raw mushroom will make you pretty ill, although the chances of fatality are next to zero.
Try it ground (sub-psychoactive doses I mean) into a powder, and use as a seasoning for steak, or added to chilli con carne, a bit of fly agaric turns a good steak into a truly wonderful one.