Freeze your marshmallows for at least 1 hour. I found that they didn’t melt as much in the oven if I did this. Place them in a freezer bag for 1 hour, they can be frozen for up to 2 months.
Whisk together your flour, baking soda, and baking powder in a medium bowl. Set aside.
In a stand mixer fitted with the paddle attachment, combine the butter and peanut butter with your sugars. Beat until light and airy, about 2-3 minutes.
Add in your egg, egg yolk, salt and vanilla and beat for another minute.
Pour in the dry ingredients and mix on low until there are no more streaks of flour. Use a rubber spatula to fold in your peanut butter chips.
Line a baking sheet with parchment paper.
Scoop out 2 tablespoons of cookie dough and flatten it with your hand. Place your marshmallow in the middle and wrap the dough around it, making sure it is completely sealed. Place the cookie dough balls on the baking sheet and chill for at least 1 hour or up to overnight. This cookie dough makes 20-22 cookies.
Preheat your oven to 350°F/175°C. Bake the cookies 6 at a time on the middle rack of your oven. Bake for 11-13 minutes. The center of the cookie will still be gooey. Allow the cookies to cool completely before removing. Line another 2 baking trays with parchment paper so you can bake more cookies while the first batch cools.
Notes
My recipes have been developed and tested in metric grams. I highly recommend using a weighing scale and measuring out your ingredients the metric way. I have provided a conversion to US cups but please note that I haven’t tested the recipe with this method. Just click on ‘Metric’ above the ingredients. Butter: I use European style butter, like Kerry Gold, in my recipes. This will make your finished bake much creamier and richer.Salt: If you don’t have kosher salt, halve the amount of salt called for in the recipe. 1 teaspoon kosher salt = ½ teaspoon fine salt.
Peanut Butter: use commercial peanut butter and not peanut butter that has oil on top. You can substitute the peanut butter for almond butter or sun butter.
Peanut Butter Chips: you can swap out peanut butter chips for chocolate chips.
Storage: keep the baked cookies in a tupperware for up to 5 days at room temperature. Freeze unbaked cookie dough balls, when ready to bake just bake for an extra minute or two.