Preheat the oven to 180C/160C Fan and line two/three large baking trays with parchment paper, leave to the side.
Whisk the plain flour, bicarbonate of soda, salt, and cornflour together in a bowl and leave to the side.
Melt your butter carefully, and then add to a bowl. Add in the sugars, and whisk the mixture together for two minutes. (I used my electric whisk, if whisking by hand, whisk for 3 minutes)
Add in the vanilla and egg and whisk again until combined.
Add in the flour mixture and beat until everything is evenly distributed and a cookie dough is formed.
Add in the Mini Eggs, and the micro eggs and mix together again.
Scoop the cookie dough using a cookie scoop for even portions, then roll into balls. Bake in the oven for 10-13 minutes.
Leave the cookies to cool on the trays for 5 minutes, then transfer to a rack to cool completely! Enjoy!
Notes
These cookies can last for three days easily, but they rarely do in my house!
I used two bags of the 90g (usually priced at £1) Mini Eggs, then a bag and a bit of the micro chocolate eggs. These are usually supermarket own ones, and I've got them before in Sainsburys, Tesco and Asda for example!
If you can't access the micro eggs, feel free to add in 200g of chocolate chips, or 100g of chocolate chips and some more Mini Eggs!