Step 1

Prepare an 8" springform tin - lightly grease the sides with butter or a baking spread, and place a circle of baking paper on the bottom (use a little butter to help it stick to the base)

Step 2

To make the cookie dough, mix the softened butter, light brown soft sugar and caster sugar together into a bowl until creamy, ideally using an electric mixer with the paddle attachment

Step 3

Add the egg, milk and vanilla and mix in

Step 4

Then add the plain flour, baking powder, salt and bicarbonate of soda and mix in. If using a stand mixer, you may need to scrape the bowl down to make sure all of the flour is mixed in

Step 5

Next add the chocolate chips and chopped Kinder chocolate and mix briefly to evenly distribute them throughout the dough

Step 6

Weigh the dough out and spilt it into three pieces (mine weighed 1343g, so it was 447g per piece)

Step 7

Press the first piece into the base of the tin and flatten it out until it is evenly spread across the base

Step 8

Use the second piece to cover the sides of the tin

Step 9

Wrap the third piece in cling film and set aside on the kitchen counter

Step 10

Warm up the spread in the microwave briefly for 20-30 seconds to loosen it to a pourable texture. Pour about half of it into the tin lined with cookie dough

Step 11

Press the Kinder Bueno bars and Kinder chocolate into the spread, you will need to break them up to get them all to fit

Step 12

Then pour over the remaining spread

Step 13

Place the whole thing in the freezer for one hour to firm up

Step 14

Remove from the freezer and cover the top with the third piece of cookie dough, making sure to seal the edges so the spread is completely sealed in. Put it back in the freezer for one hour

Step 15

When the hour is almost up, pre-heat your oven to 180C Fan/400F/Gas Mark 6

Step 16

Place the cookie pie into the oven and bake for 30 minutes. I like to put a baking tray on the shelf beneath it in case a few drops of butter escape from the springform tin

Step 17

Remove from the oven and leave to cool

Step 18

Put the cookie pie in the fridge for 4-5 hours or ideally overnight before slicing it up

Step 19

If you would like to decorate it with the Nutella buttercream, started by mixing the butter and Nutella together with an electric mixer until creamy

Step 20

Add the icing sugar and milk, and mix until smooth

Step 21

Place the buttercream into a piping bag and pipe it around the edge of the cookie pie

Step 22

Decorate with more Kinder Bueno and chunks of Kinder chocolate

Step 23

Store leftovers in an airtight container in a cool place and eat within 3-4 days