1. Pre-heat the oven to 180°C. In a stand mixer, combine the butter, sugar and vanilla. Beat until light and fluffy. Gradually add in the eggs.
2. Add in the plain flour, baking powder, cornflour and salt and beat until you have a dough.
3. Fold in the M&Ms and hundreds and thousands. Bring the dough together into a ball and wrap in clingfilm.
4. Chill for 30 minutes.
5. Using your hands, roll the mixture in to ping pong-ball sized rounds.
6. Place on to lined baking sheets, leaving space between each one so they’re able to spread in the oven.
7. Bake in the pre-heated oven for 12-14 minutes.
8. Cool for 5 minutes, then transfer to a wire rack to cool completely.
9. Take your ice cream and place a scoop on each cookie. Sandwich with another cookie and roll the sides in whatever toppings you like.