Preheat the oven to 175C/350F
Grease a muffin tray and place a biscuit on top of each hole.
When oven is at temperature, place the tray in the oven for 2-3 minutes.
Remove the muffin tray immediately.
The biscuits will have softened.
Gently mould each softened biscuit into the muffin hole, forming a cup.
Allow to cool.
When biscuit cups are cool, loosen them in the muffin moulds to ensue that they can be removed easily. It is easier to assemble the tarts if the cups remain in the muffin tray.
Spoon runny caramel (the caramel may need to be gently warmed to loosen it) into each cup.
Refrigerate for 30 minutes.
Melt the chocolate in a heat proof bowl over a saucepan of simmering water (double boiler technique).
Once melted, remove from heat and allow to thicken and cool slightly. The chocolate should still be runny but not hot.
Spoon chocolate on top of the caramel, smoothing and spreading if required.
Refrigerate for at least 30 minutes.
Remove caramel tarts from muffin tray and serve.