Heat your oven to 390F or 200C. Line a baking tray with a silicone baking mat or parchment paper.
Put two thirds of the Mini Eggs into a sealed freezer bag and bash with a rolling pin to break them up into small yet discernible chunks. Aim for around a quarter of a Mini Egg.
Pour the bashed Mini Eggs into a bowl and set aside. Add the remaining eggs to the bag , bash into larger chunks of around ½ Mini Egg in size and set aside in another bowl.
Beat the butter and sugar with a manual whisk, electric whisk or stand mixer. Then mix in the egg and vanilla essence.
Mix the flour, baking powder and sea salt in a separate bowl. Then pour them into the wet ingredients and gently mix.
Gently fold in the Mini Eggs and chocolate chips by hand.
Form the cookie dough into 8 even-sized balls and place on the baking tray, ensuring they are 5cm/2 inches apart.
Place the additional halved Mini Eggs into the outside of the cookies.
Bake for 12-14 minutes until the edges begin to brown and the tops start to crack. (Note 2)
Optional: To get perfectly round cookies use a round cookie cutter or glass, place it over the cookies as soon as they have come out of the oven and move it gently around the outside to round off any uneven edges.
Let the cookies cool for 5-10 minutes on the tray and then transfer them to a wire rack to cool completely.