Line a baking tin with baking paper and set aside near your stove top.

In a saucepan over a low heat, combine the brown sugar, butter and vanilla extract. Stir until the butter has melted, and then turn the heat onto a medium heat and allow the mixture to boil. Stir for a few minutes until the toffee is bubbly and thick (make sure you keep stirring to avoid burning).

When the toffee is done, pour onto the prepared baking tin. Smooth out with a spatula, and place in the fridge to cool while you make the cookies.

Preheat oven to 150C. In the bowl of a stand mixer, beat the butter, caster sugar and brown sugar until light and fluffy on a low speed. Add the salt, vanilla and eggs, and allow to combine for about 1-2 minutes.

Add the flour and baking soda, and beat until completely combined, using a spatula to brush down the edges if needed.

Remove the bowl from the stand mixer and add the chocolate chunks. Remove the toffee from the fridge and crumble into small chunks before adding to the cookie dough. Stir through with a wooden spoon.

Line two baking trays with baking paper. Roll small dough balls using your hands and place on the baking trays until you have used all the mixture, allowing a bit of space between each cookie.

Bake the cookies until golden around the edges. I did 10 minutes, but if you want less gooey cookies, cook them for a few additional minutes. Allow to cool completely before removing from the baking trays, and store in a container for up to a week (if they last that long).