In a food processor, pulse the cookies several times until coarsely chopped. Add the cocoa powder and salt and pulse a few more times until combined. Add the melted butter and pulse several more times until the mixture is crumbly (don’t over-pulse or the mixture will turn into a paste). Set aside.
In a large bowl, whisk together the peanut butter and Nutella until smooth.
In a stand mixer with the whisk attachment, whip the cream and sugar to a stiff peak (this can also be done by hand in a separate bowl).
Scoop 1/3 or 1/2 of the whipped cream into the peanut butter Nutella mixture and stir until evenly combined. Add the remaining whipped cream and gently fold in until just combined. If not using immediately, cover with plastic film and refrigerate.
To serve, use small mason jars or wine glasses. Alternate between layers of cookie crumble and mousse (I used approximately 1/4 cup per layer).
I used 2 bags of Milano cookies which I like because they’re not cloyingly sweet. I broke them in half before adding them to the food processor which you may or may not need to do depending on the size of the cookies being used.This recipe yields more mousse than cookie crumble but the extra mousse likely won't go to waste.