Melt butter in a heavy-based saucepan.
Add flour and stir over low heat for 1 minute.
Remove from heat and add milk, stirring until smooth.
Return to medium heat and stir continuously until boiling.
Reduce heat and cook for 5 minutes, stirring frequently.
Season with salt and pepper.
Add broccoli, remove from heat and allow to cool.
Beat egg yolks and add to broccoli mixture.
Beat egg whites until soft and fold into sauce.
Spoon mixture into an ungreased medium soufflé dish and place in a baking or roasting pan half filled with boiling water.
Bake in a preheated oven at 180°C for 45 - 50 minutes.