Prepare a rectangular shape baking tin lined with baking paper. I used the one 11 x 7 inch baking tin. Set aside.
Mix the Rice Krispies and the mixed nuts (chopped) with raisins together in a bowl. Set aside.
In a microwave safe medium bowl (it should be big enough to add all of the ingredients in), melt the chocolate and the coconut oil in the microwave. Avoid the highest power to avoid burning the chocolate. While it's melting in the microwave, check sometimes and give it a stir.
Add the Rice Krispies and the mixed nuts & raisins mixture in the melted chocolate.
Mix thoroughly to coat Rice Krispies and nuts & raisins.
Spoon the mixture into the prepared tin and press down to form an even layer, pushing the mixture into the corners and sides of the tin. Put it in the fridge.
*Take out from the fridge after about 1 hour and cut into chocolate bar shapes with a heated knife. Put back in the fridge for at least another hour to set completely before serving. I kept mine in the fridge for 3 hours.