what is your opinion re just making the cake single layer with a basic ganache or sour cream frosting?

A single layer requires more than 1/2 of the batter. Otherwise, the cake will be too thin. (These layers are not very thick.). The proper quantity of ingredients is exactly 2/3 of what's given there. You will get a somewhat thicker cake than each of the layers, but that will be the right size for a single layer cake. If you need help with the calculations, please let me know. I'd be happy to figure it out and add it to a note in the recipe.


Regarding the topping:
If a basic ganache sounds good to you, go for it! I know that for many people, there simply is no such thing as "too much chocolate." I respect that. I do think however that a sour cream frosting, especially one that is not too sweet, would be delicious, too! Either way, I recommend, if you have the time, making the praline topping, as it's quite nice. The bit of crunch, and the aroma and flavor of the toasted nuts add a lot here. ;o)

My guess is that some people will consider this cake with basic ganache chocolate overload and deem it a monstrosity. Some others will probably be super enthusiastic with such a creation. There is place in this universe for both camps and all those in between.

Ultimately it's your call since it'll be served at your dinner table. If your guests enjoy that sort of thing, they will be thrilled.

AntoniaJames will probably answer this when she sees it, but I’d think that with no gluten to build structure (the cake uses almond flour), the cake will probably sink in the middle if you made it in one layer.