自分

Let's explore "自分で" (jibun de), meaning "by oneself," and "作った" (tsukutta), the past tense of "作る" (to make). The phrase "ものです" emphasizes that it is something. The sentence clearly indicates the speaker personally made the cake. Thus, the person who made the cake is "自分" (myself/I).

「自分で」は「by myself」、「作った」は「to make」の過去形、「ものです」は強調です。このケーキは自分が作ったと述べています。ケーキを作ったのは「自分」です。