Melt the milk chocolate in the microwave in 30 seconds bursts until smooth.
Using a teaspoon or small pastry brush, cover the bottom and sides of each tart shell with chocolate. Allow to harden.
Meanwhile, place the peanut butter in a microwaveable container and heat on medium high for 30 seconds until runny.
Add the icing sugar to the peanut butter and mix to combine well.
Pour the peanut butter mix into each tart until it just comes to the top of each tart.
Drizzle remaining milk chocolate over the top of each tart and finish with a final scattering of crushed peanuts.
Allow to set for an hour and then enjoy!