This has been made in a 13cm x 35cm tin. There is enough pastry for a 22cm-24cm tin as an alternative.
Firstly make your pastry.
Combine butter, flour and salt in a food processor and process just until pastry starts to come together, add 1-2tbsp iced water and process until pastry forms a ball. Remove from processor, shape into a disc, wrap in plastic wrap and put into the fridge for half an hour.
Preheat oven to 200C. Roll out pastry and place in the tin of your choice. Line the tin with baking paper, and fill with dried baking beans. Put into the oven and bake for 20 minutes. Remove baking paper and beans, let cool, and reduce oven to 180C.
Whisk eggs with cream, combine with Onion Marmalade, and season with salt and pepper. Pour into pastry case, dot with the crumbled Meredith Dairy Chèvre and scatter the thyme leaves on top. Put in oven and bake for 20-30 minutes until the filling is set. Serve warm.