Start by greasing a 9″ circular baking pan (preferably a springform pan) then set aside. Add the marshmallows and butter to a microwave-safe bowl. Heat in the microwave for 30 seconds. Then give it a stir. Keep heating 20 seconds at a time and stirring until it is completely melted and smooth.
Mix the Trix cereal into the marshmallow mixture.
Press the Trix marshmallow mixture into the bottom of the pan and along the sides.
Place pan in the fridge while you mix the cheesecake.
In a large mixing bowl, beat the cream cheese and sugar until fully combined.
Slowly fold the cool whip into the cream cheese mixture. Make sure that it is all mixed in but do not over stir.
Pour the mixture on to the Trix crust. Use a silicone spatula or back of a spoon to even out the mixture over the crust.
Chill in the refrigerator until firm. Takes about 2 hours.