1. First make a box that is roughly 40 centimeters long, 8 centimeters wide and 8 centimeters tall out of strong cardboard.
2. Place thinner cardboard or a silicone mat so it touches the base but runs up both sides, creating a semi-circular bottom.
3. Make the biscuit by beating the sugar and butter together. Then add in the egg yolks, milk powder, water and lastly gradually incorporate the flour.
4. Roll out the dough on a floured surface to about 2 centimeters thick and bake i the oven for 10-15 minutes at 150C.
5. Meanwhile, pour some of the caramel mix into the bottom of the lined rectangular box and set in the fridge.
6. Once the shortbread is cooled, cut into the same shape as the box and place one piece on top of the caramel. Smear some caramel on top of this, and place a second biscuit on top.
7. Temper the milk chocolate and cover the base lightly with this.
8. Turn the Twix out and sit it, chocolate side down on two ramekins. Pour the remaining chocolate over the top of the Twix to cover.
9. Get some gold paper and wrap the Twix bars up - crimp the edges and serve.