Preheat oven to 160 degrees and line with baking paper a baking tray.
Melt the butter in the microwave and allow to cool. Butter must be cool or it will "cook" the egg!
In a large bowl, crack the egg and beat with a whisk
Add vanilla melted (cooled) butter, salt and both sugars and mix to form "caramel" looking sauce
Fold in the flour to form the cookie dough
Using a spoon, make 12 cookie dough balls, roll in your clean hands and place on the prepared tray, allow space to spread when they cook
Bake in oven for 12 mins at 160 degrees (for soft cookies) or at 180 degrees for crispy/crunchy cookies.