Keeping the skin on, slice the kumquats, oranges and tangerines horizontally into 3mm rounds.
Prepare a large bowl of water and ice. Bring a large saucepan of water to the boil, reduce to a simmer and then add the sliced fruit and simmer gently for 1 minute. Drain the fruit slices and immediately plunge them into the iced water.
Divide the caster sugar between two shallow frying pans, and then add 200ml water to each.
Put over a medium heat and stir to dissolve the sugar then raise the heat and reduce slightly to a syrup for 2-3 minutes. Lower the heat and then drain the fruit slices and add them to the frying pans in a single layer.
Simmer over a low heat for 1 - 1 ½ hours. Then carefully remove onto baking paper to set while you make the pastry and filling.
Meanwhile make your pastry. Place the flour, cocoa powder, ground almonds, sugar, salt and butter in a food processor.
Blitz until the mixture resembles breadcrumbs.
Pour in the egg yolks a little at a time, pulsing in between additions, until the mixture has just come together.
If necessary bring the last bit together with your hands. Wrap the pastry tightly in cling film and chill in the fridge for 15 minutes.
Preheat the oven to 185c/165c fan.
Between two pieces of baking paper, roll the pastry to a circle approximately 35cm wide.
If the pastry is too warm it may need to be chilled again at this stage.
Once rolled, lift the pastry up and gently place over the tart tin.
Carefully line the tin, lowering the pastry into the corners and pressing into the fluted sides. If there are any tears or holes, patch them up with the excess pastry at this stage.
Trim the edges off with a knife and prick the base with a fork then chill in the fridge for 10-15 minutes.
Line the inside of the pastry with baking paper and add baking beans. Bake for 15 minutes then remove the baking beans and bake for a further 10-15 minutes. Leave to cool at room temperature while you make the filling.
Put the chocolate, butter and double cream in a large heatproof bowl over a pan of gently simmering water. Stir until they have melted and combined then remove from the heat. In a separate bowl mix together the Baileys and crème fraîche.
Once the chocolate mixture has cooled slightly, stir in the Baileys and crème fraîche until the filling is all one colour.
Pour straight into the tin immediately before the filling starts to set.
Shake the tin slightly to spread out evenly and then chill in the fridge for at least 1 hour.
When ready to serve, remove the tart from the fridge and decorate with the candied fruits.