Line a 9x13-inch baking dish with parchment paper.
In a large pot over medium-low heat, melt the butter. Once melted, stir in the salt and whisk continuously until the butter turns golden brown. Watch carefully to avoid burning.
Lower the heat and add all but 1 cup of the mini marshmallows. Stir until fully melted and smooth.
Remove from heat and stir in the Rice Krispies until well coated.
Gently fold in the remaining 1 cup of marshmallows and 3/4 cup of the sprinkles.
Press the mixture evenly into the prepared pan.
Sprinkle the remaining 1/4 cup of sprinkles over the top.
Use the bottom of a measuring cup or glass to gently press and flatten the top so the sprinkles stick.
Let cool for 1 hour. Cut into bars and serve.
