In a pot on the stove, melt butter and marshmallows, stirring constantly until both are melted and evenly combined.

Meanwhile, add the Trix to a large bowl, gently coated in non-stick cooking spray.

When the butter and marshmallows have melted and been evenly combined, remove from heat and pour them over the Trix cereal.

Using a spatula, also coated in cooking spray, stir the Trix and marshmallows together until evenly combined.

Pour into a greased 9×13 baking dish and press them down flat using your coated spatula.

Let them sit for about 30 minutes to allow everything to set.

Cut into squares and enjoy.