Spray a 13x9-inch rectangular cake pan with nonstick spray or line bottom and sides with parchment paper.
Measure out brown rice cereal into a large bowl and set aside.
In a large pot over low heat, melt ghee. Add salt and white chocolate and stir until melted. Add marshmallows and stir continuously until melted. Remove from heat and pour in brown rice cereal. Quickly stir until the marshmallow mixture is well distributed and cereal is coated.
Scrape mixture into prepared pan and lightly press down to smooth top. Let cool, remove, and cut into slices.