English Translation
Take and eat as much you like.
食べなさい sounds bossy. You can say it to your kids and their friend at the same age.
But refrain 食べなさい when you offer your guests something to eat even if the guests are your close friends. in this situation, you can use the following alternative phrases.
(Casual) 好きなだけ食べてね。
(Formal) 好きなだけお召し上がり下さい。
We usually don’t say とって + 食べる. It’s redundant. So I dropped とって from my alternatives.