Preheat the oven to 180°C.
Lightly grease a 25cm loose-bottomed tart tin with butter.
Roll out the pastry on a floured surface and line the tin.
Cover pastry with cling film and chill in the fridge for 15 minutes.
Remove film, line with greaseproof paper, and fill with baking beans.
Bake the pastry case for 10 to 15 minutes.
Remove paper and beans, then bake for another 3 to 5 minutes.
Remove the case and lower the oven temperature to 140°C.
Mix golden syrup, breadcrumbs, eggs, lemon juice, and zest in a bowl.
Pour filling into the case and bake for 50 to 60 minutes until golden.
Serve tart slices with whipped cream and fresh mint.