In a medium saucepan, heat 4 cups of marshmallows over low heat, stirring constantly for about 5 minutes until completely melted and smooth.

Remove the saucepan from heat and add 4 cups of Fruity Pebbles cereal to the melted marshmallows, stirring vigorously for about 1-2 minutes.

Grease a clean countertop or parchment paper with cooking spray or butter to prevent sticking.

Transfer the mixture onto the prepared surface and flatten it into a rectangle about ½ inch thick, adding fillings if desired.

Start rolling the mixture away from you to form a tight sushi shape, using your hands to keep it compact.

Let the sushi log cool for about 10 minutes, then cut into 1-inch pieces.

Enjoy immediately or store in an airtight container at room temperature for up to three days.