Start by measuring all the ingredients out. Separate the marshmallows by 10oz and 5oz.
In a large pot on medium low heat, add in the butter. Once the butter is melted then add in 10oz of the marshmallows and the peanut butter. Allow them all to melt together. You'll notice they are separated but continue to mix until they are combined and you no longer see streaks of butter or peanut butter in the marshmallows.
Once combined, turn off the heat. Then add in the rice cereal and 5oz of marshmallows. Stir until it looks decently even, it won't be perfect because the melted marshmallow will quickly start to harden making the folding more difficult.
Now in a lined baking pan, add in the mix and gently press down to fit he mix into the pan. You are very likely going to have a little left over if you don't press down super hard. That's extra to share with the family as the Rice Krispie treats set.
Allow them to sit on the counter and completely cool before lifting them out of the pan . When they are cool, slice, serve, and enjoy!