1. Add flour, walnuts, wild garlic leaves, Parmesan to a food processor and blitz till combined.
2. Add the butter and mix again till it forms small crumbs.
3. Add the beaten egg and mix till the dough comes together, add a splash of milk if you need it to form a supple dough.
4. Knead the dough for 5 minutes on a floured surface before wrapping in clingfilm and chilling in the fridge for half an hour.
5. Preheat your oven to 180°C/Gas Mark4
6. Roll out the pastry on a floured worktop to 3mm thick and line a 25cm diameter circular dish and trim the edges.
7. Using a fork, prick the base and then blind bake until lightly golden, 10 minutes. Brush lightly with beaten egg and bake until golden and crisp, around 10 minutes.
8. Pan fry the streaky bacon till crisp, remove the bacon from the pan and set aside, retaining the bacon fat.
9. Add onion and spring greens to the bacon fat, stirring occasionally until very tender (10 minutes), season with salt and pepper.
10. Spread the onion/spring green mixture in the pastry base, top with bacon, scatter with crumbled Stilton and chopped parsley.
11. Reduce oven to 150°C/Gas Mark 3. Whisk yolks, eggs, cream and sour cream in a bowl till everything is incorporated, season to taste and pour into the pastry case.
12. Bake in the oven till golden, 30-40 minutes. The centre should have a slight wobble. Allow to rest for 10 minutes and then serve with a rocket salad and chutney.