Line an 8x8-inch pan with parchment paper. Use the butter wrapper rubbed along the inside of the pan and especially into the corners to help hold the parchment in place. If using peanuts, place ¼ cup of whole peanuts in a zip-top bag and crush with a meat tenderizer or the bottom of a heavy pan.

Set the Possible Cooker Pro to Sear/Sauté on High and allow it to preheat. Add the 2 tablespoons of butter and let it get about 50% melted before adding the marshmallows.

Add the 4 oz (2 cups) of mini marshmallows to the partially melted butter. Stir constantly until the butter and marshmallows combine into a completely smooth, glossy mixture with no lumps remaining. Do not walk away; constant stirring prevents scorching.

Pour in all 6 oz (4 cups) of Cinnamon Toast Crunch cereal. Stir until every piece is fully coated in the marshmallow mixture. Turn off the appliance and remove the pot from the heat. Keep stirring as the mixture cools slightly.

Let the cereal mixture cool for 1 to 2 minutes off the heat. Stir in the 1 cup of mini marshmallows and the crushed peanuts (if using). Then add the ¼ cup of chocolate chips and give everything a quick stir to distribute without fully melting the chips.

Transfer the mixture immediately into the parchment-lined pan. Scrape out every bit from the pot. Place a second piece of parchment paper on top and press firmly with your hands into an even, compact layer. The more you compress the mixture, the better the bars will hold together.

Let the bars set at room temperature for 1 to 2 hours, or refrigerate for 30 to 45 minutes for a quicker set. Once fully firm, lift the parchment out of the pan, peel back the sides, and cut into squares. Cut into approximately 1½ to 2-inch squares for smaller, richer pieces, or larger if preferred.