On her first appearance at Lord's, Mooney guided London Spirit to an eight-wicket victory over Welsh Fire, smoothly plotting her way to an unbeaten 61 as the home side eased home with 14 balls to spare on Wednesday.
It was another immaculate display from the world's top-ranked T20I woman player Mooney, who's also second in the ODI rankings behind her compatriot Alyssa Healy.
Her superb knock, a masterpiece of control featuring 11 boundaries and compiled off just 39 balls, gave the Spirit their first win of the campaign.
It also took Mooney back to the top of the competition's run-scoring charts as she took her total in four innings to 201.
Buttler, who's out of the rest of the men's tournament with injury and was watching from the Lord's commentary box, couldn't have been more impressed by the Australian great.
"That was a fantastic fifty, beautiful batting," he told Sky Sports.
"She raised the rate with ease after playing herself in, and is at the top of her game, picking and choosing, knowing exactly where the field is. Outstanding batting."
Chasing the Welsh side's 9-119, which always looked a bit on the low side, the elegant left-hander Mooney, who'd already pulled off a couple of stumpings as wicketkeeper, shared an opening stand of 66 with pinch-hitter Danielle Gibson, who cracked 34 from 27.
Carrying on her superb form from the Commonwealth Games, the 28-year-old took her time to get set in the powerplay but once she did, began to stroke the ball around immaculately, reaching her 50 off 34 balls with a sweet late cut.
An exquisite cover drive for four off Alex Hartley then sealed the victory, taking the Spirit to 2-122 off 86 balls which gives the Spirit still a chance of qualifying if they can win their remaining games.
"It was really nice playing here at Lord's, I'd never played here before," said a delighted Mooney, who won her second player of the match award following her dazzling unbeaten 97 against Southern Brave at the start of the tournament.
"Our bowlers did an outstanding job - and we reaped the rewards."
Spirit's England captain Charlie Dean told Sky: "Beth makes it seems so easy, a tremendous batter and a really great person, who's been a great help for me as an inexperienced captain."
