Lightly oil the setting mold, and line the bottom well with aluminium foil sealing to make a base. I used two 3.5" X 3.5" circular steel dessert molds.
Sprinkle the gelatin over water, and leave to soften/bloom.
Place the cream, milk, sugar and vanilla bean in a heavy base saucepan and simmer for 5 minutes. Taste and adjust sweetness if required. Whisk on the bloomed gelatin.
Scrape the vanilla bean to add flavour and discard shell. Strain.
Divide the vanilla bean cream mixture into 3 portions.
Leave one as is {vanilla bean layer}, stir the coffee into the second portion, and whisk the cocoa powder, melted chocolate and cream into the third.
Pour the first mixture, the vanilla bean panna cotta, dividing equally between the molds. Freeze for 30 minutes/until set.
Top the set vanilla bean panna cotta gently with the coffee panna cotta mixture. Freeze for 30 minutes, until set, then top with the chocolate portion.
Leave to set in the fridge overnight.
To demold, gently remove the foil from the base, and loosed the edges to slide out the panna cotta.
Serve as is or with a coffee sauce.