1. Prepare the shortbread base:

• Preheat your oven to 180°C (160°C fan) or 350°F. Grease and line a 9×9 inch baking tin.
• In a mixing bowl, combine the flour, butter, and sugar. Rub the butter into the flour and sugar until the mixture resembles fine breadcrumbs.
• Press the shortbread mixture evenly into the prepared baking tin, creating a firm layer.
• Bake for 20 minutes or until golden and firm to the touch. Set aside to cool completely.

2. Make the caramel filling:

• In a saucepan, melt the butter and sugar over low heat, stirring until dissolved.
• Add the condensed milk and bring the mixture to a gentle boil, stirring constantly to avoid burning.
• Let it simmer for 5-7 minutes, or until it thickens and turns a golden caramel color.
• Pour the caramel over the cooled shortbread base, smoothing it out with a spatula. Allow the caramel to set in the fridge.

3. Prepare the chocolate topping:

• Melt the chocolate in a heatproof bowl either in the microwave in 30-second intervals or over a saucepan of simmering water (bain-marie).
• Once melted, pour the chocolate over the set caramel, spreading it evenly with a spatula.
• Place the tin back in the fridge to set for at least 1-2 hours, or until the chocolate has hardened.

4. Slice and serve:

• Once set, remove the shortbread from the tin and slice into squares or rectangles with a sharp knife.