A day after breaking the women's record for most wins on the elite circuit, Shiffrin took her tally of victories to 84 with a combined time of 2 minutes 3.28 seconds.
The American star had been over half a second ahead of the pack after her first run on Wednesday morning and made no mistake in the afternoon sunshine, finishing 0.82sec ahead of Ragnhild Mowinckel (30).
The Swede Sara Hector (30) was third, 1.19sec behind the American.
"I think between the second race in Kranjska Gora (where she equalled the women's win record) and these two races yesterday and today, is the best two days of skiing I ever did," said Shiffrin.
"I feel so good with it. I love the feeling I have on GS skis right now so it's a pleasure to race. After yesterday I was quite tired, today... I just want to sleep!
"At the end of the day, these are just two runs that are one minute long. You always have energy to do that... I feel like if I focus on one good turn and then the next good turn and then keep going with it, it should be OK."
Triumph in the Italian Dolomites moved Shiffrin to within two of the overall wins record of 86 held by Ingemar Stenmark, who dominated the men's slalom and giant slalom disciplines for a decade from 1975 before retiring in 1989.
Shiffrin could very well move level with Stenmark before next month's World Championships in Courchevel and Meribel as this weekend come two races at Spindleruv Mlyn in her favoured slalom - the discipline in which she has claimed 51 victories.
A 10th win of the season also pulled Shiffrin further away in both the giant slalom and overall standings, leaving Lara Gut-Behrami (31), who finished fifth on Wednesday, trailing by 118 and 611 points in the respective rankings.
"I don't have a goal for the numbers. This season I was thinking if I could get four wins, five wins, maybe six, then that's the most I could possibly get. And that would be a great season," added Shiffrin.
"I don't need more. But I really like skiing this way so I keep pushing and when I'm on the start gate on the second run, I'm like 'I don't need it, but I want it'. So I'm going to try my best and that's how I feel mentally."
Shiffrin has bounced back in emphatic style after a nightmare Beijing Olympics last year where she failed to win a single medal.
She is heavy favourite to add to her world golds in France and set records that will stand for generations to come.
