Make your own pastry, or roll out the pre-made pastry to be as thick as a £1 coin, and use it to line a 20cm pie dish.
In a large saucepan add the syrup, butter, zest, juice, ginger and cardamom and stir until melted and well combined.
Remove from the heat and tip in the breadcrumbs. Mix well then spoon the mixture into the pastry case, flattening and smoothing down with the back of your spoon.
Arrange the pastry leaves around the top of the tart, and brush all exposed pastry with the beaten egg. Bake for 35-40 minutes or until the pastry has turned golden brown and the filling has puffed up and darkened a little. Let cool before diving in.