Line a 34cm x 24cm sping roll tin and preheat the oven to 200 ℃
Melt the butter in a pot over a low heat. Once melted remove from the heat and add the flour.
Once combined place back on the low heat and add the milk. Stir until a smooth think sauce emerges.
Separate the eggs and add the yolks to the white sauce. Stir until thick and then take off the heat.
Place the egg whites into a cake mixer bowl and beat until stiff peaks form. Gently fold the eggs whites through the sauce.
Pour into your prepared tin and cook for 12-15 minutes
Once cooked tip onto a clean tea towel.