01 -
In a big, sturdy pot, mix together the butter, sugar, and melted ice cream. Let it boil on medium heat.
02 -
Turn the heat down a tiny bit. Keep stirring nonstop for 7–10 minutes, till your candy thermometer says 234°F.
03 -
Take the pan off the heat. Toss in both kinds of chips and stir until everything is smooth and melted.
04 -
Stir in the marshmallow until it’s all combined nicely.
05 -
Pour into an 8x8 pan. Sprinkle on the decorations if you’re using them. Let it cool down completely.
06 -
Pop the block out of the pan, then slice it into about 24 squares.