The simpler the ingredients become, the harder it is to make a good meal.
When the ingredients are simple, it becomes more difficult to make a delicious meal.
ご質問ありがとうございます。
"so that"構文を使う訳は思いつきませんでしたが、比較級の文章は以下の通りです:
① "The simpler the ingredients become,"=「食材が簡単になればなるほど」
"the harder it is to make a good meal."=「おいしい食事を作るが難しい。」
② "When the ingredients are simple,"=「食材が簡単なときは」
"it becomes more difficult to make a delicious meal."=「おいしい食事を作るのが難しくなる。」
ご参考に。