1 Prepare a blind-baked sweet pastry 10in tart shell and leave it in the mould. I use bottomless tins.
2 Beat the soft butter and brown sugar together until well combined and creamed. Then trickle the eggs in slowly, a little at a time.
3 Add the cinnamon, lemon juice and zest and mix well. Fold in the raisins and walnuts and give it a good mix.
4 Scoop the mix into the prepared pastry case and smooth out with a wet palette knife.
5 Bake at 160C/Gas Mark 4 for roughly 45 minutes, checking and spreading the mix flat as you go.
6 Allow to cool slightly before cutting into slices and serving with lots of crème fraîche.