I need some help!

I have tried this mud cake recipe 3 different times and it turns out really bad for me.
The cake cooks fine but when it cools it's like a big hard rock the edges are crusty and almost impossible to cut. I have read several posts from people here who have used his recipe and had great results but not me!

I have even tested my oven and its fine, Any suggestions or tips?

I have an order for a chocolate mudcake this weekend and I am going nuts!

CHOCOLATE MUDCAKE

1 cup plain flour
1 cup self raising flour
1/2 cup good quality dark cocoa powder
1/2 teaspoon bicarb soda (baking powder)
2 1/2 cups sugar
8oz dark chocolate, chopped
8oz butter
3/4 cup hot water
1/2 cup buttermilk
2 tablespoons oil
2 tablespoons coffee powder or granules
4 eggs

1. sift flour, cocoa and soda into bowl. Stir in sugar
2. melt chocolate and butter in pan until smooth. Add and stir in water
3. gradually stir in choc. mixture to dry ingredients
4. whisk buttermilk, oil, coffee, and eggs in sparate bowl until combined.
5. Add into cake mixture and combine well. Pour into prepared tin. (Make sure it is lined well with baking paper (leave a 2cm collar above the rim).
Bake for 1 hour and 40 mins on 160 degrees C. (315deg. F/Gas 2-3) until skewer comes out clean

That is the exact recipe I use and I have never once had a problem with it. I even converted it into a vegan recipe for a couple I'm doing a wedding cake for. Turned out perfectly.

Though I did notice that I don't need to cook the cake for the full hour and 40 minutes. I probably cook it for less than an hour. I'm not really sure on the time. I just keep checking on it and when I poke it with a toothpick and it comes clean I pull it out. The cake continues to cook when you let it sit to cool. My cakes are always moist and soooooooo good. I've never had hard edges or dry cake. But then I don't let it cook for almost 2 hours either. I don't know what kind of mess I would get if I did, something resembling charcoal maybe?

Try it again but this time don't cook it for the whole amount of time the recipe calls for. Keep an eye on it and when the cake seems done pull it out and let it rest. I check my oven and everything thinking it was something on my end and all was working properly. I think there is something up with the recipe honestly. Typo maybe?

What exactly is a mud cake? If someone wouldn't mind telling me! Sorry, I've been wondering this and figured this was a good thread to ask the question.

Mudcake is an extremely rich chocolate cake that tastes much like brownies. I make it all the time and eat it plain without any icing. It's a chocolate lover's dream.

Wow! How is it that I didn't know about that! Better check it out!

First:
Get out your thermometer and check the accuracy of your oven temperature. Stack your racks into position - test the oven rack exactly where the cake is usually placed. You may be surprised at the results.

Second:
Mudcake is not a high-riser. It is not a thick cake. If the recipe requires a "collar" around the pan, then the cake batter is poured too thick to cook completely without overcooking. Try larger pan.

Last:
For this recipe, my cookbook says "160° C. 9" springform pan 1 1/2 hours" [140° C fan-forced]. Your 10 mins longer could be the problem. Test for doneness after 1 hr 20 mins.

Note:
* As the "muddiness" depends upon long slow cooking, I would knock it back to 140° C [120° C fan-forced] for 2 hours.

* Try 120° C [100° C fan-forced] for 2 1/2 hours for the next cake, if you are adventurous. I use this one [fan-forced].

The edges will also soften so it is best to make the cake more ahead of time than you normally would say a buttercake... Natis recipe is a treat so give it a whirl..