Use double the quantities.

Use a cooking dish which has double the area of the base of the one you would use for 4 so that the height of the pasta bake is the same as it would be for 4 in the smaller dish.

Same cooking time, not double. If you are using the same dish as for 4 you would need to cook for a bit longer but not double - can't give you a precise figure as to how much longer which is why using a larger dish is safer.

Ok, thanks, Loro. I'm scared.

Taste it as you go along to see if its done. That's what the top chefs do, innit. 

But that means opening the oven door, pulling it out, burning myself, tasting it, dropping the fork into the pasta bake, retrieving the fork, burning myself, putting it back in the oven, and closing the oven door.

Talk about effort.

 Yeah, fair point.

order a pizza

No way, man. No way. They always cook a meal for me when I go over theirs. I need to step my game up.

Hopefully it turns out alright, otherwise they're getting crumpets.

pretend you made it & hide the boxes

anyway lots of pizza places do pasta dishes now

just add cheese

Follow Velvet and El Loro's advice and you'll be fine.

If it all goes wrong, follow Pirate's advice and order some pizza!