Ganache8

Truffles are best at room temperature for texture and flavour. The ganache can take 24 hours to "crystalize"--firm up some more. Truffles can last in cool conditions up to 14 days but I've been told you'll be able to tell if they've gone off. Best to freeze (for longer storage) in well-sealed container & warm up slowly in the container to prevent off-flavor absorption and condensation. Have you checked on your ganaches to see if they have firmed up? Best of luck!

Fruit crumble & vanilla ice cream. Keep crumble topping in freezer (equal weight brown sugar, all-purpose flour, coarse oatmeal with slightly less butter cut in). Whatever looks good at market or if you have frozen fruit in freezer (berries, rhubarb)--toss with lemon juice, brown sugar, little flour or corn starch & cinnamon optional, dot with butter, cover with crumble & bake--serve warm with ice cream.

I think you're good to go. I've used a panna cotta recipe from the Grand Finales book with good success but used dark chocolate & cocoa powder. I was worried as you were about the chocolate flavour coming through. Biggest problem was cocoa powder settling on bottom of mold as little specks. You can decrease the amount of gelatin to counteract the firming qualities of chocolate--good experimenting!