To make the white sauce, take 1oz butter and 1oz flour. The secret is to make sure you incorporate plenty of air into the roux (the mixture of flour and butter), so really work it without overcooking it. Slowly add a little cold milk and carry on working it in until it's the right texture. The longer you work it, the more air you get into the mixture and the smoother it will be. When it gets runnier, switch from a spatula to a whisk, then add one Knorr Stock Pot, the finely-chopped parsley and just a dash of cream.
