The Evils of Baking

WTF?! : The noise heard from my kitchen on the completion of one of my baking attempts.

I'm pretty good at following a recipe, not to say my cooking is fantastic but I have yet to give anyone food poisoning and believe me I have come close. But something happens whenever I try to bake.
I have tried cookies, ginger snaps and something that i cant remember what it was supposed to be but came out as coal.

All of which were burnt despite the cooking time insisting i leave them in for another twenty minutes, all were crunchy and tasteless and scrapped of baking trays that I could hear seething at me.
Most famously was my attempt at chocolate cake last Christmas were by it looked good despite the drippy nasty tasting icing, but when I went to cut it (I didn't freeze it I swear) EVEN THE BREAD KNIFE, you know the BIG knife shaped like a RAZOR could not cut through it! and it weighed a stone.
IT WEIGHED A STONE- IT WAS A ROCK!

I blame the muscovado sugar, only dark was available.

Yes I substituted an ingredient, (it was supposed to be light muscovado) but I thought: "what the hey? can't be that much of a difference right?" WRONG! so very, very, ashamedly wrong...

anyway moral of the lesson:  Don't substitute an ingredient unless you've tried it before. unless you KNOW it works.

In the meantime i'll try baking with the proper ingredients.... thinking Victoria sponge...