Preheat the oven to 350 degrees F. Line cupcake pan with muffin liners. Set aside.

Beat together brown sugar, apple sauce, oil, and peanut butter in a large bowl until light and fluffy. Add the egg and vanilla, stirring until combined.

Combine dry ingredients from flour - a pinch of salt in a medium bowl. Add alternately with the milk to the peanut butter batter. Fold in the coarsely chopped nutter butter cookies. Fill the prepared cupcake pan about ¾ full.

Bake for 18 to 20 minutes in the preheated oven, until the top of the cupcakes, spring back when lightly pressed. Cool in the pan for 5 minutes before removing it to a wire rack to cool completely.

Meanwhile, prepare the frosting. Beat together powdered sugar with softened butter until well-combined, about 3 minutes on medium speed. Add vanilla and heavy whipping cream and beat for another minute. When cupcakes have cooled, pipe frosting onto cupcakes. Place cupcakes on a sheet pan and place in the freezer for 30 minutes or until the frosting is set.

Make the ganache. Heat heavy cream in a medium saucepan over medium heat until it begins to boil. Remove from heat and pour over the chocolate. Mix until chocolate has melted. Let ganache slightly cool before dipping.

Remove cupcakes from the freezer. Carefully dip the cupcakes one at a time into the ganache. Top with mini nutter butter cookies or nutter butter crumbs. Repeat with remaining cupcakes. Let set before serving.