Avoid a "floury" white sauce

At the beginning of a white sauce always cook off the butter and flour over low heat for 1 minute to ensure the finished sauce doesn’t have a “floury” flavour. Remove from the heat before whisking in milk and returning back to the heat to thicken. 

Should I grease my baking tins?

This helps stop food sticking. Brush the tin with melted butter or use some baking paper with a little butter on it to rub around the inside of the tin.