Line your rimmed sheet pan with parchment paper. You want the paper large enough that it comes up the sides as well. A spritz of non-stick spray will help the paper stick to the pan. Then spray the top of the paper with non-stick spray.
Set your large pot on the stove over medium-high heat. Melt the butter completely, and then continue cooking the butter until the milk solids sink to the bottom and become amber-brown. Reduce the heat to medium-low.
Add the white chocolate chips, vanilla bean paste, salt. Mix until the chips are fully melted. Add 10 oz (1 bag) of mini marshmallows. Stir to coat in the brown butter white chocolate mixture, and continue stirring until the marshmallows are melted and smooth.
Dump in the rice cereal and the remaining 5 oz (½ bag) of mini marshmallows. Stir until the cereal and extra marshmallows are coated in the gooey marshmallow mixture. There should be no extra dry cereal at the bottom. The extra marshmallows will melt a little bit.
Pour the brown butter rice krispie mixture into your prepared sheet pan. Scrape all the remaining sticky bits out of the pot. Spray your hands with non-stick spray and press the mixture gently into the pan. It should reach all sides and into the corners and be nice and level.
Allow the pan to cool for 30 minutes. Remove the Rice Krispies from the pan and cut into 16 equal bars.
Store in an airtight container on the counter for up to a week.
Keyword Brown Butter, Rice Krispies, Vanilla Bean, White Chocolate