Chop marshmallows into small cubes about 1/2 inch square.
Spray an 8x8 cake pan with nonstick spray. Set aside.
In a large pot, melt butter over low heat. Continuously stir butter and watch it closely as it begins to brown. It will first melt, then turn white and foamy, then begin to turn golden brown and smell nutty. Remove the pot from the heat as soon as it begins to brown.
Add chopped marshmallows and salt to the pot. Use a rubber spatula to stir the marshmallows into the butter. The butter will be hot enough to melt the marshmallows, just keep stirring. I like to leave some bigger chunks of marshmallow- you do not need them to melt 100%. (You can return pot to heat if necessary.)
Add cereal to the marshmallow mixture and stir gently until everything is evenly coated.
Transfer mixture to your prepared pan. Use a rubber spatula sprayed with nonstick spray to pat down the rice krispies into the pan. Do not make it too compact or your rice krispie treats will be hard.
Let cool for at least 1 hour. Remove rice krispie block from pan and put on a piece of parchment paper. Use a serrated knife to cut squares into desired size. Drizzle with melted chocolate using a spoon or a piping bag (see recipe notes). Sprinkle with ground graham cracker. Enjoy!
Rice Krispie treats are best enjoyed the day they are made. They can be stored in airtight container for up to 3 days. Use parchment paper between the layers to prevent sticking.