In a large mixing bowl, beat together the softened unsalted butter, brown sugar, and granulated sugar until light and fluffy, about 3-5 minutes.

Add creamy peanut butter, large egg, and vanilla extract to the mixture and mix until all wet ingredients are fully combined.

In a separate bowl, whisk together all-purpose flour, baking soda, baking powder, and salt.

Gradually add the dry mixture to the wet ingredients, mixing gently until just combined.

Fold in mini marshmallows and peanut butter chips carefully.

Scoop the dough onto a parchment-lined baking sheet, cover with plastic wrap, and chill in the refrigerator for 30 minutes.

Preheat oven to 350°F (175°C) and bake cookies for 10-12 minutes until edges are golden brown.

Let cookies cool on the baking sheet for about 5 minutes before transferring to a wire rack.