First make your pastry if you're making your own or get it out of the fridge if using shop bought. Steam or boil your vegetables until soft then drain.
Fry the onion in the butter with the mustard powder and dried herbs over a medium heat until soft. Allow to cool slightly and mix with the vegetables.
Stir in the cheese. At this point I divided the mixture into two. I added the stilton to one half and left the vegetables chunky. I then mashed the rest of the vegetables together with the cheddar to make it more palatable for the kids.
Cover a baking sheet with greaseproof paper. Roll out your pastry on a lightly floured surface and use a small saucer or large pastry cutter if you have one to cut out circle shapes. Placing the pastry circle on your hand spoon in some of the vegetable mixture. Be careful not to overfill - make sure you can close the pasty firmly. Brush the edges with egg wash and press tightly together to seal. Place on the baking tray. Repeat with the remaining pastry re-rolling as necessary. I made four large stilton pasties and four mini cheddar ones.
Brush the lot with egg wash and bake at 200°C(fan)/220°C/gas mark 7 for 20 minutes until golden brown.