01 -
Place butter in a large microwave-safe glass bowl and heat until completely melted. Whisk in the sugar and evaporated milk, mixing thoroughly until combined.
02 -
Heat the mixture on high power for 3 minutes, then give it a good stir. Return to the microwave and heat for another 2 minutes on high.
03 -
Stir the mixture well, making sure to scrape down the sides of your bowl. Heat on high for 3 additional minutes, then stir and check the temperature with a candy thermometer. You're aiming for exactly 234°F. If needed, continue heating in 1-2 minute intervals until you hit that magic number.
04 -
Take the bowl out of the microwave and immediately add your chocolate chips. Stir energetically until they're completely melted and the mixture looks silky smooth. Fold in the marshmallow creme and vanilla, mixing thoroughly until no white swirls remain.
05 -
Pour your fudge into a greased 9-inch square pan (or a 13x9-inch pan if you prefer thinner pieces). Let it cool completely at room temperature before slicing into squares.