1) Heat the oven to 180˚C.
2) Using the butter and crushed shaved parmesan, grease and dust the ramekin moulds for the soufflé.
3) Heat the butter in a saucepan until melted and then add the flour and cook out the flour until you have smooth paste.
4) Heat your milk in a separate saucepan then gradually add to the roux mixture whisking or stirring all the time until all the milk has been added.
5) You should have a smooth sauce base - add the Dijon mustard and season to taste.
6) Remove from the heat and add the butternut squash purée and the egg yolks combining it all together.
7) In a clean mixing bowl whisk the egg whites to form stiff peaks and add the lemon juice and whisk again.
8) Whisk 1/3 of the egg whites into the soufflé base - now carefully fold in the remaining egg whites - adjust the seasoning if needed.
9) Fill the ramekin moulds with the soufflé mix and smooth off with a pallet knife - using your thumb create a grove around the rim of the ramekin.
10) Place in a hot oven for 20 minutes until golden brown and well risen - serve at once.