In a mixer bowl, beat the butter and sugar with the paddle attachment until light and fluffy. Add the eggs one by one, followed by the orange juice, and mix until incorporated.
Continue by adding the Olympus Super Spread Smooth Peanut Butter and finally pour in the self-rising flour. Once the mixture achieves a creamy texture, remove the bowl from the mixer. Grease and flour cupcake tins or use non-stick disposable paper liners.
Fill each mold equally, covering three-quarters of the way, and bake in a preheated oven (fan-forced) at 190°C for approximately 25 minutes. Remove from the oven and allow them to cool completely.
Meanwhile, prepare the buttercream. In the mixer bowl, beat the butter with the whisk attachment until fluffy and add the remaining ingredients. Once they are incorporated and form a rich cream, place it in the refrigerator for a short while to cool and set. Using a piping bag with a decorative tip, frost each cupcake.