1. Preheat oven to 180°C. Line two baking trays with baking paper.
2. Whisk baking powder, flour and salt together in a bowl. Set aside.
3. In the bowl of a standing mixer, cream butter and both sugars on medium speed until creamy, about 1.5 mins. You can also do this by hand if you don’t have an electric mixer.
4. Add the egg and vanilla extract and beat till it is smoothly incorporated, about 1 min.
5. Add the Milo and beat on low speed to incorporate, about 30 sec.
6. Still on low speed, add the flour mixture and beat till smoothly incorporated, about 45 sec.
7. Scoop out heaped tablespoons full of dough and drop them on the lined baking trays about two inches apart as they’ll need space to spread as they bake.
8. Bake for about 12 to 14 mins, rotating the trays halfway through baking. Bake till the edges are crisp and dark, and the middles are still a little soft (they'll look a little undercooked/shinier in the centre).
9. Let the cookies cool in their trays on a wire rack for 10 mins before transferring the cookies onto a wire rack to cool completely.
10. The cookies will keep in an airtight container for up to four days at room temperature, or up to a fortnight in the fridge.