Preheat oven to 180C/350F and spray a 10 or 12 inch skillet with cooking spray. (I use Bake Easy).

Break up your sleeve of Oreo's by hand into larger and smaller chunks and place in a medium sized bowl. Take out a handful and leave to one side if you plan on pressing Oreo's into the top of the cookie.

Add your chocolate chips, flours, bicarbonate of soda and salt into the bowl of Oreo's and mix until all the chocolate and Oreo's are coated in flour. Leave to one side.

Place sugars and butter into a large bowl, or the bowl of your stand mixer and beat until light and fluffy, about 2 mins on med-high speed.

Add in eggs and vanilla extract, scraping sides of bowl as necessary, and mix until well incorporated and smooth, about 1 minutes on med-high speed.

Tip your flour and chocolate mix into your egg mixture and mix on low until a soft dough forms.

Tip 2/3 of your dough into your prepared skillet and smooth until level. I just went in with my hands as I found it easiest, use a spatula/spoon if you prefer.

Spoon 1/2 cup salted caramel sauce all over the cookie dough and use the back of a spoon to smooth it out over the cookie dough - leave a 1/2 inch gap around the edge to prevent leakage.

Dot the remaining 1/3 of cookie dough around the skillet and then smooth it over (again I used my fingers) it doesn't matter if not every single bit of caramel is covered, but it probably will be!

If you have reserved some Oreo pieces, press them into the top of the dough.

Place in the oven for 23-28 minutes until risen, golden and the middle is set. An inserted skewer into the centre will have a few crumbs on it, but the outside will not.

Leave to cool in the skillet completely before making the topping: Place double cream into a medium sized bowl and whisk until it holds a peak. If you over whip it and it starts to get broken up and lumpy, add a little splash of milk and fold in with a spatula, this should bring it back together.

Place into a piping bag fitted with an open star nozzle and then pipe all around the edge of the cookie and a larger "star" in the centre.

Crush 3-4 Oreo's into fine crumbs (I used a mini food processor) and then sprinkle over the peaks of cream.

Place 1/4 cup salted caramel into a small heatproof bowl and microwave for 20 seconds to make it more workable.

Drizzle salted caramel all over the skillet cookie with a spoon or squeezy bottle.

Skillet cookie will keep covered, in the fridge for 4 days. Microwaving it for 20-30 seconds will make the centre extra gooey again, or serve at room temperature. It's great whatever the temperature!!!