Put your Crème Eggs in the freezer overnight or for a minimum of 4 hours.
Preheat the oven 180C (160C Fan) and grease your muffin tray.
In a large bowl mix together the butter and sugar until it is light, creamy and fluffy.
Add in the flour, cornflour, eggs and vanilla and mix until all the ingredients are incorporated and a dough is formed. Fold through the chocolate chips and add in the milk mix again until it forms a dough.
Remove 260g of cookie dough, and place in a separate you will use this for the lid of your cookie cups. Leave to one side.
Split the remaining dough into 12 equal balls and press them into your muffin tin. I found the best way to do this is by using the floured top of a rolling pin.
Fill all 12 cookie cups with a single crème egg.
Using the remaining 260g of dough, split this into 12 equal smaller balls and place on top of your cookie cups.
Press the lids down to ensure that there is no gaps that your crème eggs could leak from
Put your mixture in the oven for 12-15 minutes until they are golden brown.
Leave your cookies to cool in the muffin tray; it makes them easier to get out.