In a bowl, cream together the softened butter, brown sugar, and white sugar until light and fluffy.
Beat in the egg and vanilla extract until well combined.
In a separate bowl, whisk together the flour, baking soda, baking powder, and salt.
Gradually fold the dry ingredients into the wet mixture until a soft dough forms.
Gently mix in chopped Kinder pieces and chocolate chips, if using. Don’t overmix.
Cover and chill the dough in the fridge for 30–60 minutes to help the cookies hold their shape and stay chunky.
Preheat your oven to 180°C (160°C fan) / 350°F. Line a baking tray with parchment paper.
Scoop large balls of dough (about 2–3 tbsp each), place on the tray spaced apart, and bake for 12–14 minutes or until the edges are golden and centres look slightly underdone.
Let cookies cool on the tray for 5 minutes before transferring to a wire rack. The Kinder chunks will be gooey and delicious!