'astonished face' is a perfectly acceptable phrase in written English.
You can use it whenever you'd like to describe the facial expression of someone who is surprised or shocked. For example, "John had an astonished face when he found out he'd won the lottery."
When the child climbed into the salon chair, she met the hairstylist's astonished face with an enormous smile.
It was obvious that he was unarmed & no one looking at his mild, astonished face, could have imagined him capable of violence.
The Mail might as well have put an "astonished face" emoji at the end of its headline: "Former Argos security guard from London estate defeats African dictator to become PRESIDENT of Gambia".
In her questionnaire she confirmed she wanted to be the new Marilyn, and in a dozen ways, from the blonde curled hair to the bright red lips to the gorgeous pouts and poses, she was.She acted too, though it was the Breasts that stole every scene, full in Leslie Nielsen's astonished face in "Naked Gun 33 1/33.
George looked up at my astonished face, and I was trapped in his sweet story.
The banty-rooster-tough gangster, Tom Powers, who shoved that famous half grapefruit into the astonished face of his gun moll (played by Mae Clarke) in "The Public Enemy" in 1931.
A group of minglers on the front lawn welcomed me to the party with astonished faces.
As Yigael walks Elana home & says goodbye, "his voice broke, and he averted his face, astonished by the tears that welled up in his eyes".
Perreau, who likened the concealed cavern to "a cathedral or grotto," was astonished to find himself face to face with a gigantic sculpture nicknamed "the monster" because of the roar from nearby subway trains.
Travelling in Europe, she was astonished by her first face-to-face exposure to Velázquez, in the Prado.
Face to face, we were astonished by the similarities in our handwriting, gestures and sleep posture.
