Grease pan and set aside
Place butter in pot.
Melt butter over medium-low heat. Stirring frequently.
Butter will melt.
Then turn clear golden & start to turn brown & smell nutty. Stir frequently, scraping up any bits from the bottom. Don't take eyes off the pot, period b/w butter browning & burning is less than 1 min
As soon as butter takes on nutty color turn off heat and stir in marshmallows and vanilla.
The heat from the melted butter should melt them. If not, turn back on low heat until the marshmallows are smooth.
Remove the pot from stove and stir in salt and cereal together.
Quickly spread into prepared pan. I use my silicone spatula sprayed with a little baking spray to press evenly in pan. Let cool.
By the time I wash the dishes, they are ready to cut...
As Deb, from Smitten Kitchen says, " ...cut into squares and get ready to make new friends."