First up, line 2 large baking trays. Pop your butter and sugars into a large bowl and whisk together until smooth and paler in colour.
Pop in the egg and Vanilla Extract and whisk again until smooth. Sieve over the flour, cornflour, Baking Powder and Bicarbonate of Soda and mix until the dough comes together. Finally mix in the Chocolate Chunks and 100g crushed mini eggs.
Divide your cookie dough into 100g pieces and flatten each piece of dough. Pop a square of Chocolate into the centre of each piece of dough. Wrap the dough around the chocolate piece and roll into a ball, repeat for each piece of cookie dough and pop onto your lined baking trays spaced well apart. Push your left over mini eggs into the tops of the cookie dough balls.
Pop your trays of dough into the freezer for 30 minutes. 10 minutes before baking , preheat your oven to 200°C/180°C fan/Gas Mark 6. Bake your cookies for 15-18 minutes until golden brown. Leave to cool on the tray for 10 minutes and then pop onto a cooling rack.
Your cookies are best served warm and freshly baked for a wonderful gooey chocolate centre. You can pop them back in the oven for a few minutes to re-heat if left to cool.