The former Red Devils star has called on the Dutchman to make a concerted effort to land the Bayern Munich midfielder and believes Ed Woodward must prove his worth this summer.
United opened talks over a 48.5 million euro move for the Germany international when the club faced Bayern in the Champions League in April.
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"The first player I’d bring in is Toni Kroos," he said in a blog for Paddy Power.
"He’s a top-class central midfield player but United need five or six to get anywhere near the top of the Premier League again."
With Van Gaal set to leave all transfer negotiations to Ed Woodward, Scholes has called on the executive vice chairman to prove his worth this summer, following a disastrous transfer window 12 months ago.
"Edward Woodward has an awful lot to prove this time that he’s good enough at his job," he added.
"He has to bring the players in that the new manager wants. It’s obvious that last year he didn’t manage to do that. If he doesn’t, we are not going to get anywhere near the top."