Step 1

To make the pastry, put the plain flour, cocoa powder and caster sugar in a bowl and stir together

Step 2

Add the butter in chunks and use your fingers to rub the butter and flour mixture together until it resembles bread crumbs

Step 3

Add the milk little by little (you may not need it all, or you may need a little bit more) and form into a dough

Step 4

Wrap in cling film and chill in the fridge for 30 minutes

Step 5

Pre-heat your oven to 180C Fan/200C/350F/Gas Mark 5

Step 6

Using a light dusting of flour on your surface and rolling pin, roll the pastry out to fit a 9" tart tin

Step 7

Smooth the pastry out in the tin and prick the bottom with a fork

Step 8

Scrunch up some baking paper and cover the pastry, then add baking beans. Bake it for 15 minutes

Step 9

Remove the pastry from the oven and remove the baking paper and baking beans. Put it back in the oven and bake it for 10 minutes

Step 10

Once it comes out of the oven, reduce the temperature to 160C Fan/180C/350F/Gas Mark 4

Step 11

To make the custard filling warm the double cream in a pan on a low-medium heat

Step 12

Once it starts steaming, take it off the heat and add the chocolate. Leave it for a few minutes, then stir until smooth and all of the chocolate is melted. Leave to cool for 5 minutes

Step 13

Whisk the eggs and sugar together, add the orange extract and whisk in

Step 14

Slowly pour the chocolate and cream mixture into the egg and sugar mixture whisking as you pour. Once mixed, transfer to a jug

Step 15

Put the pastry case on the oven shelf first, then pour the filling in using the jug

Step 16

Bake for 30 minutes, then leave to cool completely before decorating

Step 17

To decorate, whip the cream with the vanilla and icing sugar using an electric whisk

Step 18

Pipe onto the tart, or spread on with a spoon

Step 19

Decorate with some Terry's Chocolate Orange slices if you like

Step 20

Serve immediately, store leftovers in the fridge and eat within 2 days