Line a 9x13 baking pan with aluminum foil and lightly grease with baking spray. Set aside.

Add the butter to a small, light-colored saucepan. Melt the butter over medium-high heat, and stirring occasionally, stir until the butter is browned and smells nutty. Remove from heat and pour into the bottom of a large pot. 

Add two cups of mini marshmallows into the measured cereal, then pour the rest into the large pot with the browned butter and allow to melt over low heat, stirring occasionally. 

After marshmallows have melted, remove from heat and mix in vanilla extract and pinch of salt. Pour in cereal mixture and stir until well combined. Dump mixture into greased cake pan and lightly press to even it out. Avoid pressing too hard on the mixture, otherwise it will make it compact and hard. allow them to set at room temperature for 30 minutes or so to set up. When you're ready to serve, lift foil out of pan, cut into squares and serve. Enjoy!