Melt the butter in a saucepan.

Add the granulated sugar, soft brown sugar and salt respectively. Cook at low heat until all is melted and keep stirring every now and again. Once the mixture is emulsified, it will be thick and shiny with a delicious butterscotch smell.

Now place the butter and sugar mixture in a mixing bowl. Then add the egg and egg yolk in. Mix well after each addition. The mixture will be slightly runny and light in colour.

Next, you add the salt, baking soda and vanilla extract to the mixture. Stir well.

Then fold the flour in and quickly stir the batter. Try not to spend too much on stirring and mixing. Though you want the flour to be well combined with the mixture without leaving any lumps. 

You will have a very thick batter-like cookie dough. If it feels too soft, you can keep it in the fridge/ refrigerator for about 5-10 minutes before you put the chocolate chips and bake the cookies.

When you’re ready to bake, put 1 cup of the chocolate chips in the cookie dough and mix well.

Bake the cookies in the preheated oven at gas 4/ 180° C/ 350° F for about 10-12 minutes until they are soft to touch but look firm on the outside.