I reckon you could "create your own" in terms of a recipe for this. I think you'd need a spring form or loose bottomed pan, then you'd want a cake that will be reasonably robust - I'd imagine something like the sponge for a Swiss roll would be what you need there. A standard chocolate mousse would be fine I think (the sort with egg whites is my preferred option - I think the chocolate would give it enough stability without gelatin) and then you could use a non baked cheesecake for the topping - I'm not sure if theirs is vanilla or white chocolate.
In terms of recipes:
Mary berry's can't go wrong chocolate cake is my go to for a sponge but it's a full size two layer cake made with only two eggs so I think it would require a big tin.
Mousse wise a chocolate variation on this white chocolate one would be my choice: www.google.com/amp/s/www.deliciousmagazine.co.uk/recipes/white-chocolate-mint-mousse/amp/ but thinking about it further, one made with gelatine might give a less solid cake?
Then cheesecake wise if you want a white chocolate one on top this one is good:
www.bbcgoodfood.com/recipes/malt-chocolate-cheesecake
And a ganache would just be your ratio of dark chocolate to cream - a thin, pourable ganache is usually 2:1 cream to chocolate but you could reduce the cream quantity to make it thicker.