Mix together all of the chocolate crumb crust ingredients. Set aside.
For Chocolate Pudding Layer
Whisk together the milk, cream, sweetener, cocoa powder, and salt. Heat to just before boiling over medium high heat.
Using a ladle, scoop up about a cup full of hot liquid. While whisking briskly with one hand, steadily pour the hot liquid with the other hand into the egg yolks. Once combined, pour quickly into the pot of hot liquid and whisk.
Continue to cook over medium-high heat for another 3 minutes or until thickened, whisking constantly.
Once the pudding has thickened, remove from the heat. Stir in the vanilla.
Lay some plastic wrap directly over the top of the pudding and put it in the refrigerator to chill.
For Peanut Butter Mousse
Using a hand mixer, beat all the mousse ingredients except the whipped cream together in a mixing bowl.
Gently fold in the whipped cream.
Press the chocolate crumb crust into the bottom of an 8- by 8-inch baking dish or in the bottoms of 8 6-ounce mason jars.
Add a layer with all the peanut butter mousse next.
Add a layer with all the chocolate pudding last.
Chill. Top with a dollop of whipped cream just before serving.