Melt the butter and the peanut butter in a large pot over medium-low heat. Add the 10 ounces of mini marshmallows while constantly stirring until completely melted, then remove from heat.

Add in the cornflakes, stir until fully coated. Mix in the remaining 1 ounce of mini marshmallows and the peanut butter chips then gently combine your mixture without over mixing.

Use some nonstick cooking spray on a large scooper to scoop out about 10 peanut butter cornflakes balls (equal in size) onto a parchment baking sheet. Gently lay out the peanut butter cookies to about 1-inch thickness. Your cookies should still be fluffy so don’t pack them to avoid density.

Let your cookies set for 20 to 30 before serving.