To make the chocolate ganache: Place chopped chocolate in a medium heat-proof bowl and set aside. In a small saucepan over medium heat, bring cream just to a boil. Immediately pour cream over chocolate and let sit without stirring for 1 minute. Then, whisk mixture gently until completely melted and smooth. Allow to cool slightly before using.

To make the peanut butter mousse: In a large bowl using a mixer fitted with the paddle attachment, beat cream cheese, peanut butter, powdered sugar, and vanilla extract on medium-high speed until fluffy and smooth.

In a medium bowl using an electric mixer fitted with the whisk attachment, whisk heavy cream until it holds its shape (it should have the texture of shaving cream). Using a spatula, gently fold half of the whipped cream into the peanut butter mixture, then fold in the other half.

Fill each jar with two alternating layers of peanut butter mousse and chocolate ganache. You can use other ingredients such as chocolate candy or whipped cream in between the layers or as toppings.