Spray an 9"x 13" (or 8"x 8" for thicker bars) casserole dish with nonstick cooking spray.
In a 4 quart sauce pan, melt butter on low heat. Do this slowly, you don’t want burned or brown butter here.
Once butter has melted, keep heat on low and add mini marshmallows.
Once marshmallows begin to soften and melt, add peanut butter.
At this point, you will need to constantly stir the mixture so the peanut butter does not burn and the marshmallows can evenly melt (won’t take too long, about 5 minutes or so).
Once, mixture is combined and melted, turn off heat and remove pan from stove.
Add rice krispy cereal to sauce pan and stir until evenly coated with mixture. This is sticky stuff so do your best to get it all combined.
Pour mixture into casserole dish (it will look very loose.) Spray your hand with some nonstick cooking spray and pat down the mixture until firmly compacted.
Allow 30-45 minutes for treats to set up.
Video
Notes
If you prefer a slightly thickerbar, use an 8x8-inch baking dish.
Also, for all you budget-conscious shoppers, I have made this recipe with the store brand cereal, marshmallows, butter and peanut butter and these treats still turn out delicious.
If you’re a Krispies treats purist, just leave out the peanut butter, they’ll still be gooey.
As with all Rice Krispies treats, they are best eaten the day they are made.
Store in an airtight container if you don't eat them all the same day. I like to warm them up in the microwave for about 5-10 seconds when they start getting a little stale.