Place the chopped Mars Bars, cocoa powder and cream into a microwave safe bowl. Melt on 50% power in 30 second bursts until melted (stir each time). (If using a Thermomix, melt on 50 degrees, 2-3 minutes, Speed 2).
Place the rice bubbles into a large bowl and pour over the melted Mars Bar mixture.
Stir until well combined.
Lightly spray 2 mini muffin baking trays with cooking oil.
Place spoonfuls of the mixture into each hole and press down firmly. Place into the fridge for 10 minutes to set.
Meanwhile, melt the white and milk chocolates in the microwave on 50% powder, 2-3 minutes (stirring every 30 seconds). If using a Thermomix, melt on 50 degrees, 3 minutes, Speed 2.
Remove the chocolate crackles from the tin and place onto a flat board.
To make the Christmas puddings, spread a little white chocolate over the top of the puddings, add 2 slices of spearmint leaves and a red M&M.
To make the reindeers, place 2 pieces of cut pretzels as antlers and a red M&M as a nose.
Store in the fridge in an airtight container for up to 5 days.