Heat the butter in a pan.
Add flour into it and quickly stir well until flour evenly cooked..
Now add 1 cup of milk and stir continuously that no lumps are formed.
When mixture is thicken well switch off the stove and add pinch of salt, Herbs and black pepper.
Now add cooked pasta out of remained 2 portions of pasta into white sauce and mix well. Garnish with fresh herbs.