After "could not", is it "help but notice" or "help noticing"?

Question

I have read and heard examples of both "could not help but notice" and "could not help noticing".

Hello, penguins. I could not help but notice that you have a hat that magically brings things.

— The Penguins of Madagascar: Happy King Julien Day! (2009)

Again,

Well, I'm sorry to have to put this to you, but I could not help noticing that you were miming.

— A Bit of Fry and Laurie: S02E01 (1990)

We hear and read both versions. Which one is grammatical—are they both? Please mention the nuance of each.

Answer 1

Both are perfectly grammatical and both are used when one feels very strongly compelled to do something and can't stop themselves doing something.

can't help but

We cannot help but intervene here, before you throw your life away on drugs!

My mom can't help but meddle in my love life, even though I'm 30 years old!

can't help doing

She couldn’t help laughing when she saw it.

I shouldn’t have said it but I couldn’t help myself.

I've heard the former more frequently, and I feel it's a more colloquial phrase.

In some cases, I would say one of the forms is more common. For example,

I couldn’t help thinking he was asking for trouble.