Oh, glorious! So worth popping a trouser button for and being permanently heavier for that once in a lifetime experience, lol.
Do you shop at Costco? They've got these delicious gigantic rich chocolate gateau cakes there at over 2KG each. I tried to find out the number of calories in the whole cake just for the hilarious shock factor, but they somehow get out of putting a nutrition label on them here in brexit Blighty, so I couldn't tell. So, I got creative and found out the calories per 100 grams of a similar, but much smaller, ie normal sized, Tesco cake from the label, then multiplied it up and got... 8500! I got fat just looking at that giant thing! Sooo tempting to buy it, but no, it's meant to feed a whole roomful of people.
I do not shop at costco, but your Chocolate gateau cakes sound delicious! Funny, how they got out of a full nutrition label.....and very nerdy of you to do all of that math to find estimated calories.