Preheat your oven to 180c and line 2 baking trays with baking paper.
Place your butter and sugars into a bowl of an electric mixer (or hand mixer) and beat until combined and fluffy.
Add in your egg and vanilla and beat until the egg has been incorporated.
Add in your flour and bicarb and beat until a dough forms.
Place in your caramilk chunks and fold in until the chunks are dispersed evenly throughout the dough.
Roll out into balls with 2 tablespoons of mixture and place on a baking tray, leaving about 2 inches between each ball. Flatten this slightly with the back of the spoon. These cookies do turn out quite large, read the alternate instructions at the end for smaller cookies.
Place in the oven for 13-15 minutes, until the cookies are golden on the edges and flattened out.
Remove from the oven and leave to cool completely before removing from the tray.
These can be stored in an airtight container for a week at room temperature.