In a large pot over medium heat, melt butter, about 2-3 minutes.
Stir in mini marshmallows and cook for 2-3 minutes while stirring, until melted.
Once the marshmallows are melted, stir in the rose water.
Take the marshmallow mixture off the heat. Stir in the gluten-free rice cereal and pistachios. Stir until cereal is completely coated with the marshmallow mixture.
Pour into an 8x8 inch or 9x13 inch baking pan that has been sprayed with cooking spray or lined with parchment paper. Spray the back of a spatula or your hands with cooking spray and press into the pan so that it's an even layer.
Sprinkle over the top with chopped pistachios, culinary rose petals and fleur de sel or other sea salt. Let set completely.