And a follow-up on the roll cake.

Used this recipe as a base: https://www.allrecipes.com/recipe/278040/triple-chocolate-roll-cake/

I get why roll cakes aren't common. They're much harder than layer cakes. This recipe in particular runs up against the limit of structural viability for a roll cake.

You make around 3 cups of filling for 2 cups of batter, and you want the cake to be an even half inch thick all the way through. Too thick and it tears when rolled, too thin and it tears when separating from the parchment. Both happened to me.