Preheat oven to 180°C. Lightly grease with additional butter or baking spray 18 mini muffin forms.
Break off small pieces (approximately 15g in weight) of dough (3cm balls) and press into baby muffin trays (each muffin cup is 5cm in diameter) using your fingers. Trim any sides where the pastry is higher than the tin. Prick bases and bake for 12 minutes or until pastry is a light golden brown. Remove from oven and using gloved hands or a tart tamper press the centre cavity down to create a larger, neater cavity. Transfer cases to a cooling rack and cool completely.
Pour in salted caramel to half fill the cases and set aside to set. (approximately 30 minutes).
Place chocolate and butter into a bowl. Sit bowl over a small pot of water set over a gentle heat. Stir until melted and smooth.
Pour chocolate onto caramel to be level with top of tart cases.
Chill until set.
Serve immediately or package in airtight containers with baking paper between each layer and refrigerate for up to 7 days. Alternative freeze for up to 3 months.