Line an 8-inch tin with parchment paper, and place to one side.
Place the mini chocolate chips in a bowl and place in the freezer until needed. It helps them keep their shape when you add them in later and the mix is a little warm.
Melt the white chocolate and peanut butter together in either a double boiler over a gentle heat or in a microwave on 50% power in 30-second increments.
Once melted add it to the rice krispies in a large bowl and gently mix together and then leave to cool for about 20 minutes stirring occasionally.
Once cooled to about room temperature add in the mini marshmallows and mini chocolate chips and very carefully mix it all together.
Place the mixture into the prepared pan and gently flatten out into an even layer. Place your tray in the fridge to set; they will usually be set in 2 hours but leave it overnight if possible. Once set remove and cut into squares.
Store in an airtight container in the refrigerator for up to one week.