Prepare a loaf pan by spraying lightly with cooking oil and lining with parchment paper so the paper sticks to the pan. Then lightly spray the parchment paper to prepare for the treats.
Melt 3 Tbsp butter in a medium pot. Add ½ tsp salt and cook the butter until brown and toasty over medium heat. You want the butter to be brown and you may see brown bits floating.
Remove from the heat and add marshmallows. Stir consistently until marshmallows begin melting. Once marshmallows have started to dissolve, add pot back over low heat and continue stirring until fully melted.
Crush 1½ cups of Rice Krispies. I just roughly crush them in my hand as I add them to the melted marshmallows.
Stir so everything is coated. Add the remaining ¼ tsp salt and add the remaining 1½ cup Rice Krispies and mix until everything is coated evenly.
Don’t use your hands, the marshmallow may be hot! Using another piece of parchment paper, or the flat bottom of a glass, press lightly into the corners and flatten the treats. You can also give a light dusting of cooking spray to your surface to help keep it from sticking.
Allow treats to set for at least an hour.