Toast the chopped walnuts over medium heat until fragrant and slightly toasted. Set aside to cool.
For best results, chill the whisk attachment (if using a stand mixer) and bowl in the freezer for a few minutes. Beat the heavy whipping cream until stiff peaks form. Add in powdered sugar and vanilla, whisk until combined. Set aside.
Using a hand mixer or stand mixer, combine the room temperature cream cheese and peanut butter until smooth and creamy. Blend in powdered sugar until smooth, mixture will be a bit thick.
Divide the whipped cream in half. Half of the whipped cream will be used for layering the parfaits, the other half should be added to the peanut butter cream cheese mixture. Mix at a high speed until well incorporated into the peanut butter, until a smooth consistency is reached.
Using 6 small dishes, mugs, jars, etc. layer the bottom of each dish with cubed banana bread, followed by peanut butter mousse, whipped cream, walnuts, and chocolate chips. Repeat layers until the top of the dish is reached. Chill in the refrigerator for at least an hour before serving. The mousse will set up once chilled. Can be made several hours in advance.
If serving the following day, chill ingredients separately and assemble just before serving.
See the link in my blog post for my go-to banana bread recipe. I used that recipe and just added mini-chocolate chips without the peanut butter chips, but those would certainly be great too!
I used an all natural peanut butter which is a bit thicker and less sweet than a standard Jif peanut butter which may change the consistency and sweetness of the mousse.