Mix together the powdered sugar, butter and peanut butter for about 1 minute.
Form approx. 20 balls and place in the fridge until you melt the chocolate.
Finely chop the chocolate and place on top of a double boiler with the oil, over simmering water. Stir gently and frequently until melted.
Place the muffin liners on your working surface. Remove the chocolate from the heat, but keep the bowl on top of the pot of hot water to mantain it in liquid form.
Pour 1 teaspoon of melted chocolate in each mini muffin liner, using the teaspoon to cover the walls of the liners with chocolate. Transfer them to the fridge until the chocolate has hardened completely.
Remove the chocolate cups and the peanut butter balls from the fridge. Place 1 ball in each cup and press with your finger until flat.
Add 1 teaspoon of jam on top of each cup and flatten the surface with the back of the teaspoon.
Cover each cup with melted chocolate, making sure you distribute it nice and evenly.
Allow to cool down or transfer to the fridge until fully hardened.