Have all of your ingredients measured out and ready to go because you want to move at a pace where things do not start to cool down too soon.
Melt your butter in a large pot, on low heat allow butter to bubble up and brown while stirring it frequently. It will get frothy with dark brown bits at the bottom.
Add in 10 oz of mini marshmallows into the brown butter mixture while still on low heat.
Add vanilla extract, cinnamon, and salt into the pot and keep mixing it all until the mixture is completely smooth.
Cut the heat completely off and add in the Rice Krispies. Mix them in until almost fully combined and then mix in the remaining marshmallows.
In a greased baking dish of your choice, 9x9 or 9x13, spread it all out evenly but do not press it down super hard, you want most of the cereal to not be smashed and dense.
After it completely cools, flip it out onto parchment paper and cut it how you want and enjoy!
