Preheat the oven to 350 degrees F. Place paper or foil cupcake holders into cupcake/muffin pans.
In the bowl of an electric mixer, combine the brown sugar and oil. Turn on the mixer to a low speed and mix in the eggs. Let the sugar, oil, and eggs mix while sifting together the flour, baking powder, soda, and salt in a separate bowl. Set this mixture aside.
In another small bowl, mix the vanilla into the milk and set this aside as well.
Bring the water to a boil and pour over the cocoa and whisk it until it is smooth.
To the egg mixture, alternately add the flour mixture and the milk mixture beginning and ending with flour. With the mixer off, scrape down the sides of the bowl after each addition.
With the mixture at a low speed add the cocoa. Scrape down the sides of the bowl and pour this mixture into the prepared cupcake pans. Bake the cupcakes for approximately 15 - 18 minutes or until tester comes with crumbs. Cool completely.
For the Peanut Butter Mousse:
Using electric mixer, beat peanut butter and cream cheese in large bowl to blend.
Add powdered sugar and 2 tablespoons vanilla extract and beat until well blended than remove from bowl.
Using clean dry beaters, beat 2 cups whipping cream in a clean mixing bowl until stiff peaks form; fold into peanut butter mixture in 4 additions.
For the Chocolate Ganache:
Place the chocolate chips and the corn syrup in a heatproof bowl.
Bring the heavy cream to a full boil.
Pour the cream over the chocolate and whisk it until smooth then set it aside.
Cut a cone out of each cupcake with a knife.
Put Peanut Butter mousse either in a ziploc baggie or cake decorating bag and snip off a small piece at the end.
Fill each cupcake with the peanut butter mousse and continue on top making a mound of the mousse.
Take the cupcake cake and either dip into the bowl of ganache on an angle or use a spoon to pour ganache on top of the peanut butter mousse mound.