Make an ice cream base of choice, I prefer a custard base but it's just a matter of preference. If doubling the ice cream in this recipe like I did, make 2 batches. This will give you a larger ice cream to treats ratio. Most machines will only fit one batch at a time.
Measure out 150 grams (3 cups) of Cocoa Pebbles for each batch. Place in a large temperature proof bowl.
Pour one batch of heated ice cream base over the Pebbles and mix to release the cocoa flavoring. Let sit for 10 minutes to steep.
Strain the cereal out, you may end up with some mushy cereal that goes through the strainer but this will not affect the texture that much.
Put the ice cream base into the refrigerator to chill for a few hours.
Make the cereal treats. Place 3 tbsp of butter in a large saucepan and melt on low.
Once the butter is melted, add 10 oz of marshmallows and stir until completely melted.
Turn off the heat and add 6 cups or 300 grams of Fruity Pebbles. Mix to combine and immediately add to a greased or parchment lined and greased shallow baking pan . I used two 9.5 inch silicone pans but you can use one long shallow baking sheet or pan and just cat it in half.
Use a greased sheet of parchment paper to smooth it out flat. You want it to be rather thin since you are using two for this sandwich. Too think and it will be too difficult to eat.
Let cool, and churn the ice cream.
Pipe or spoon the ice cream on top of half of the cereal treats and place the other half on top like a sandwich.
Put into the freezer to fully harden overnight, and then cut into squares. Enjoy!