Cheap, easy and takes less than 20 minutes.
Start boiling up the spaghetti
While that’s doing, use some scissors to chop up your bacon
Add a drop of oil to a pan and fry the bacon
Add the cream, cheese and egg to a bowl and mix; separate the white from the yolk with an egg strainer (or a fork). You can use the leftover white in omelettes, etc..
When the spaghetti is cooked (10-15 minutes after you put it in) drain it, then put it back in the pan.
Add the bacon and sauce.
Keep stirring it for a minute or two. The heat of the pasta cooks the egg. Make sure the egg doesn’t scramble into lumps.