This is a bit of a work in progress. I made this cake up because I had apples to use up and was craving something chocolate-y. It's quickly made with ingredients which I usually have on hand, and it tastes pretty good, but it's not five-star-terrific yet. So if you choose to try it and come up with suggestions to improve it, I'd be very grateful!
I used erythritol in place of sugar, but of course you can use sugar or xylitol. I think half brown sugar or evaporated cane juice would be very good, too.
With 2/3 cup sugar it's probably not very sweet, so if you're sweet toothed, use 3/4 cup of sugar or other sweetener.
Don't overbake it or it will get dry. I found that the toothpick should not come out completely clean. The cake is ready when it feels soft and springy pressing the top slightly, 35 minutes in my oven.