The 24-year-old graduated from the Magpies academy and made five first-team appearances before joining Paul Warne’s side permanently last summer.
The Gateshead-born player had been on the books at Newcastle for 14 years after arriving from Darlington in 2006.
It was the first time Barlaser had faced his boyhood club as the Millers held United to a 1-1 draw at the New York Stadium on Tuesday.
Barlaser told themillers.co.uk: “I had a few mates who were in the stands and my family came down for the game as well.
"I enjoyed getting the chance to showcase what I can do against a team that I obviously have a big affiliation with.
“Playing against top-flight teams is always enjoyable for me because you get a lot more time on the ball and it isn’t as frantic.
“I was pleased with how I played today and collectively as a team and on a personal level I’m happy with my performance.
Meanwhile, Burnley have passed up the opportunity to sign Thomas Robert, son of former Newcastle star Laurent, following a trial period.
LancashireLive reports that the 20-year-old had been training with the Clarets. Instead, he’ll now join up with ambitious League Two side Salford City in a bid to win a contract.
Robert played his football in Scotland last season with Airdrieonians before going on trial with Celtic.
The winger is eager to sign for a club in England as he looks to accelerate his promising career.