Preheat your oven to 190C/170C Fan and line Two 8″ Circle Cake Tins with parchment paper, and leave to the side for now.
Whisk/Mix the Plain Flour, Bicarbonate, Salt and Cornflour together so its evenly distributed – leave to the side.
In a larger bowl, melt the Butter. Add in the two Sugars, and whisk for about 2 minutes so the sugar starts to dissolve and the mixture is smooth. Add in the Eggs and the Vanilla, and whisk again briefly till smooth.
Add in the Dry Ingredients, the two different chocolate chips, the Mini Eggs, and mix with a spatula till a thick cookie dough is formed.
Press the mixture into the bottom of the two different tins – I weighed it out so they were the same as it made baking them easier and more even.
Bake in the oven for 25-30 minutes, until the top of the cookie bake looks ‘dry’ and doesn't wobble.
Leave the cookies to cool in their tins for about 10 minutes, then leave to cool fully on a wire rack.
In a stand mixer, beat your Butter for a couple of minutes till really smooth and supple.
Add in the Icing Sugar 1/2 at a time and fully beat in before you add the other half.
Add in the Vanilla Extract and beat the buttercream for about 4-5 minutes until smooth and fluffy. If you think its still a little stiff, add in a couple of tbsps of whole milk, or boiling water and beat till you have the texture you want.
Pipe your Buttercream onto the bottom Cookie, and place the second cookie on top.
On the top cookie, decorate with the rest of the Buttercream and some more Mini Eggs if you wish!
I used a large amount of Mini Eggs in this recipe, but you can swap it to the Galaxy Golden Eggs, M&M Eggs, etc! Some eggs don't hold their colour well once baked however.
This amazing Cookie Cake will last for 3 days after baking, but I won’t be surprised if it lasts less than a day.