Melt marshmallows, butter, and brown sugar over medium heat stirring constantly.
Pour melted mixture over cereal.
Use a greased spatula to combine.
Once cereal and marshmallow mixture are well combined, stir in the TWIX Bites.
Pour immediately into greased pan.
Allow to cool, cut into squares.
Notes
I use a pan lined with parchment paper and sprayed with non-stick. I also use a smaller pan than 13x9 (smaller pan = thicker treats). Spray your hands with non-stick to pat down the treats into the pan.