Add people.
You can only make the restaurant bigger on the inside by going up levels.
Finally, create fake profiles, cause you get a free ingredient from them each day, another for getting the quiz correct each day.
You can trade with them, and finally, a tip with the quiz. open a second tab. if you get the question wrong, immediately close the restaurant tab after the red X appears, then reopen it. you will get another go at the quiz if you close it quick enough, until you get the ingedient for the correct answer.