In a bowl, mix together the cream cheese, icing sugar and vanilla extra to form a paste.
Pop open the can of croissant pastry and carefully unroll. You'll see that the triangles of pastry and lightly scored between each one - kinda smoosh them together to fill in the gaps (best way I can describe it!)
Gently roll out the pastry to make it a bit wider.
Mix the cinnamon and demerara sugar together in a bowl and then sprinkle all over the pastry.
Spread the paste filling down along the middle of the pastry lengthways. Sprinkle with more cinnamon if you wish
Starting at one end of the pastry, fold over to cover the fillling and squeeze together to seal, brush on some water to help it stick.
Carefully form into a ring and place onto a greased flat baking sheet - you may need an extra pair of hands to help!
Cook in a 200C oven for 10-15 minutes until the pastry is golden, some of the filling may ooze out, but it wasn't too much when I made it.
Whilst the King Cake is cooking, make the topping by mixing the icing sugar and cinnamon together and adding water a tablespoon at a time to make a runny paste.
Take the cake out of the oven when cooked and transfer to a serving plate. Pour the cinnamon icing over the top whilst warm and cover with either shop bought sugar sprinkles, or if you can't find them make your own, quite easily by placing a couple of spoonfuls of demerara sugar into a plastic food bag (one for each colour) add a drop of food colouring and shaking about until the sugar becomes coloured.