To Make the the Peanut Butter Cupcakes:
Preheat the oven to 350 degrees and prepare a muffin tin with cupcake liners.
In a small bowl, mix together the flour, baking powder and salt. Set aside for later.
In a medium sized mixing bowl, cream together the butter and sugar until light and fluffy. Add the peanut butter, eggs and vanilla and beat well. Next, the dry ingredients and the buttermilk, alternating between each and scraping down the sides of the bowl as needed.
Fill the cupcake liners 2/3 full and bake at 350 degrees for 20-23 minutes or until the cakes lightly spring back when touched and a toothpick inserted in the center comes out clean.
Cool for 10 minutes before removing to a wire rack to cool completely.
To make the Chocolate Frosting:
Whisk together the melted butter and the cocoa powder. Slowly mix in 3 cups of powdered sugar. Once the powdered sugar has all been added, whisk in the milk and vanilla extract until the frosting is smooth and no lumps remain.
To Decorate the Owl Cupcakes:
Using a plain round frosting tip, pipe a swirl of chocolate frosting onto each cupcake.
Place 2 vanilla wafers into the center of the chocolate frosting.
Add one orange Reese's pieces right between the vanilla wafers to be the beak.
Pipe a tiny amount of frosting onto the vanilla wafers and affix 2 brown Reese's pieces for the eyes.
Add 3 peanut halves to each side of the cupcake to be the wings.
And finish by placing 2 yellow Reese's pieces to the bottom of the cupcake to be the owl's feet.