Pre-heat the oven to 200°C (400°F) Gas 6. Put a baking sheet in the oven to pre-heat.
Make or use shop bought all butter short crust pastry. Roll out the pastry to a size bigger than the tin.
Line a shallow 23 cm (9 in) tart tin with the pastry and bake blind.
When done, remove and allow to cool. You can do this way in advance.
Meanwhile, gently warm the butter and syrup together in a pan - just enough for the butter to melt but not letting the mixture get too hot.
Remove the pan from the heat and allow the mixture to cool a little.
In another bowl, whisk the eggs, cream and lemon zest together.
Gradually whisk in the warm butter and syrup mixture, then pour the mixture into the pre-baked pastry case.
Place the tart on the baking sheet in the oven and bake for 25 - 30 minutes or until the centre is set.