Sam Kerr and Fran Kirby both scored twice as last season's runners-up raced into a six-goal half-time lead.
Melanie Leupolz and Canada international Jessie Fleming both also netted in the opening period before Guro Reiten completed the rout less than five minutes after the break.
"I think in the first half we were unbelievable," England striker Kirby told uefa.com.
"We set the tone from the beginning. We were really happy to come away with seven goals and three points. Everyone played an amazing game."
English champions Chelsea sit top of the Group A table, three points clear of Wolfsburg with whom they shared a 3-3 draw last month.
The Germans visit Juventus later on Tuesday.
This was the biggest winning margin in the inaugural Champions League group stage, although someway short of the all-time record -- Apollon's 21-0 victory over Ada Velipoje in 2012.
Chelsea suffered a first-half nightmare of their own when losing 4-0 to Barcelona in the 2020-21 final in May.
The other early game saw Ukrainians Kharkiv held by Icelandic side Breidablik to a goalless draw in Group B.
The top two in that group, Paris Saint-Germain and Real Madrid, go head-to-head in the French capital later in the day.