I finally found the peeerfect swiss roll recipe where the cake layer is not too hard and it rolls easily without cracking up too much!
I adapted the recipe off the Joy of Baking website. There is even a video that shows you a step-by-step approach on how to re-create the recipe in your own kitchen.
Although the website termed it Chocolate Sponge Cake, it is actually a chocolate mousse recipe that doesn't require flour or butter. The chocolate mousse layer is then assembled like a swiss roll with raspberry flavoured whipped cream.
I would personally recommend to reduce the amount of sugar used in the recipe. Nevertheless, the recipe yields a melt-in-your-mouth swiss roll where the main calories comes from the cream filling. So if you have a sweet tooth and yet is trying to watch that waistline of yours (yes, I agree. Life is complicated!), then go easy on the cream filling. :)