Preheat the oven to 350 degrees F.
Beat butter and sugar with a mixer until light and fluffy.
Add eggs and beat until smooth.
Slowly mix with peanut butter.
Combine flour, baking powder and salt in a separate bowl. Sift. Add half the flour mixture to the butter.
Pour in milk and vanilla, continue to mix.
Add the remaining flour mixture and at low speed mix everything until smooth.
Add chocolate chips and mix by hand.
Fill the forms 3/4 with the dough and bake for about 22 minutes until the edges turn golden.
Beat the butter and peanut butter in a mixer until a smooth creamy paste is obtained.
Add icing sugar, salt and a little milk, mix until fully turned on. Add extra milk only if necessary for a softer consistency. If you need to make the glaze thicker, then add icing sugar.
Frost the cooled cupcakes. Garnish with melted chocolate or caramel topping if desired.