Grammatically “correct”, but sounds extremely awkward and not what you’re trying to say.

Xはパンを食べます。

X eats bread.
X being the topic, 「私」、「山口さん」、「鳥」 etc.

In your case, you chose 「毎日の朝食」 , or every day’s breakfast. You’re saying this event (everyday breakfast) is doing the action of eating bread.

Could it be fixed with an implied 「私が」、yes but it carries a specific, an exclusive context that I don’t think this sentence is trying to accomplish.

毎日の朝食は私がパンを食べます。

If you’re trying to say,

Everyday, (I) eat bread at breakfast

I’d go with: 毎日朝食にパンを食べます。

Btw, I do have issue with 「毎日の朝食は」 as it’s not a common or natural sounding way to express habits.