01 -  In a large bowl, beat the butter, brown sugar, and granulated sugar until light and creamy, about 2 minutes. 
 02 -  Add the egg, egg yolk, vanilla, and salt. Beat until well combined. 
 03 -  In a separate bowl, whisk together flour, baking soda, and baking powder. 
 04 -  Gradually mix the dry ingredients into the wet until just combined. Fold in the chocolate chips and sprinkles. 
 05 -  Divide dough into 8 large balls (about 100 g each) and place on a lined baking sheet. Chill for 30 minutes. 
 06 -  Preheat oven to 175°C (350°F). 
 07 -  Bake chilled dough balls spaced well apart for 13–15 minutes, until golden around the edges but soft in the center. 
 08 -  Let cool on the pan for 5 minutes before transferring to a rack to cool completely.