Mitchell scored his first senior goal in the 3-2 win.
On Mitchell, who also assisted Benteke's effort, the Belgian said: "It was a great ball and I'm really delighted for him, for his first goal. He deserved it, he's been really good every time he played. I'm really pleased for him."
The frontman also had a word for goalkeeper Jack Butland: "I think we know the story of the 'keeper: it's never easy. He's been positive, really professional and I think today was a great chance for him to show again that he's a top goalkeeper."