The Norwegian international notched his sixth goal for the Light Blues with a close range finish in the second half.
Aasgaard was also involved in the first two goals for Ryan Naderi and Dujon Sterling, before super sub Bojan Miovski secured all three points.
The 23-year-old says the squad were delighted with the victory at a crucial point of the season.
Speaking to RangersTV, he said: “The mood is really good in the dressing room. We knew we could go top of the league if we won, so that was a big incentive.
“I am enjoying being back on the pitch, it has been a rollercoaster season for me.
“It is about persistence and staying strong. It was brilliant to score, I scored against them last time they were here.
“We were managerless and we didn’t win that day so that one felt good today.
“I am too, but now we have to look to the next one.”
After the Gers went 2-0 up, the visitors netted on the stroke of half-time, before Aasgaard restored the two-goal lead.
United pulled another goal back with 18 minutes left, before Miovski fired home with five minutes remaining.
Aasgaard was delighted with the three points, but knows there are still areas to improve on ahead of the trip to Falkirk next week.
He added: “It is good to get the job done over the 90 minutes. I think it was a bit of a rollercoaster game.
“In games and in training we have a good squad and we all look forward to the games.
“The manager talks about the games being cup finals, but he said to us after the match that it is all about the next game.
“We have to recover, train well and then we go again.”
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