(from Life is Sweet by The Hummingbird Bakery)
115g butter, softened
110g caster sugar
100g soft light brown sugar
1 large egg
125g peanut butter, smooth or crunchy
165g plain flour
3/4 tsp bicarbonate of soda
1/4 tsp salt
1/4 tsp baking powder
50g mini marshmallows or chopped larger marshmallows
Preheat the oven to 175°C. Line three large baking trays with parchment paper.
With an electric whisk, cream together butter and sugar for about 5 minutes on a medium speed until light and fluffy. Add the egg and peanut butter to the mixture and beat for 2 more minutes. Sift together dry ingredients and add them to the butter-sugar-mixture. Beat on a lower speed for a few moments until all is incorporated, scraping down the sides of the bowl as you go. Fold in the marshmallows by hand.
Using a tablespoon, form the cookie dough into balls (weighing about 30g each). Place these balls of dough on the prepared baking sheets, leaving 5cm between them.