Peel the oranges and cut the peel into thin strips. Place the strips into a saucepan and cover with water. Bring to the boil and as soon as the boiling point is reached use a sieve to drain away the water and immediately refresh the orange peel in a bowl of ice water. Repeat this process 2 more times. This takes the bitterness out of the zest.
Cut the oranges in half and squeeze the juice through a sieve into a saucepan. Add half of the sugar to the pan and bring the mixture to the boil. Add the blanched orange peel to the pan, turn the heat to low and cook until tender. Remove from the syrup, allow to cool then coat with the remaining sugar. Cut the strips into a small dice ready to fold through your truffle mixture.
Place the chocolate in a bowl. Bring the double cream to the boil and then mix with the chocolate until the mixture is smooth and glossy. Add the Grand Marnier to the mixture and stir in the diced orange zest. Pour the truffle mixture into a tray and refrigerate until set.
Once set, cut the truffles into squares or use a melon baller to shape. Dust with cocoa powder to finish.
«You can make candy from any citrus fruit in the same way; a mix of orange, lemon, lime and grapefruit is particularly nice.»