The 2019 Fifa Puskas Award nominee, who has scored six goals in her last five games for Valerenga, replicated her impressive form in her side's first leg triumph over the Congolese.
The Indomitable Lionesses edged past Ethiopia to advance and were rewarded with a third-round meeting with DR Congo. Earlier they got a walkover after Equatorial Guinea's withdrawal.
In this match, Charlene Meyong broke the deadlock as she put the hosts in front just 28 minutes into the match at Stade Ahmadou Ahidjo.
Two minutes later, Nchout scored her second goal that turned out to be the winner for Alain Djeumfa's side to earn a 2-0 first-leg lead.
The result helps Cameroon put one-leg in the fourth round of the qualifying series ahead of their trip to Stade des Martyrs in Kinshasa for the reverse fixture on Tuesday.
The winner between Cameroon and DR Congo after Tuesday's tie will take on either Nigeria or Cote d'Ivoire in November.