Method –

1. Preheat oven to 180 degrees (160 degrees for fan ovens) or Gas Mark 4.
2. In a bowl, rub in the vegan margarine and flour with your fingertips until the mixture comes together in a ball.
3. Press the dough into a greased 20cm square tin and fork all over.
4. Bake for 20 to 30 minutes in the middle of the oven until lightly golden.
5. Leave to cool.
6. Make the caramel – put the custard powder in a bowl and gradually add the oat cream until you have a smooth paste.
7. Place the vegan margarine, sugar and condensed ‘milk’ in a saucepan, and add the custard paste. 
8. Heat the ingredients on a fairly high heat, stirring constantly, for approximately 20 to 30 minutes. The mixture will need to reach the firm ball stage, or 116 degrees on a sugar thermometer. To test the mixture has reached the firm ball stage, without using a thermometer, drop a small amount of the mixture in a bowl of cold water. the mixture should form a firm ball in your fingers. If it doesn’t, continue to cook, stirring constantly to prevent burning. 
9. Pour the caramel over the cooled shortbread. Leave to set.
10. Once set, melt the chocolate in a double boiler and spread over the top of the caramel. 
11. Leave to cool and cut into squares with a sharp knife.
12. ENJOY!