Preheat oven to 200°C/180°C fan forced. Lightly grease 9 holes of a round bottom patty pan. Use a 7cm round cutter to cut 9 rounds from the pastry. Ease rounds gently into the prepared holes.
Divide custard evenly between the pastry cases. Top with strawberry slices. Bake for 18 minutes, or until set but still a bit wobbly. Set aside to cool (the custard will firm up on cooling).
Sprinkle the caster sugar over the base of a heavy-based saucepan. Place over medium heat and watch as the sugar dissolves, melts and becomes a deep caramel colour. Don’t stir, but you can tilt and swirl the pan as needed to make sure all the sugar is dissolved.
Use a spoon to carefully drizzle the toffee over the tarts. Leave to cool and set. Serve within 30 minutes.
