Pre-heat the oven to 170C (fan-assisted oven) and line two baking trays with greaseproof paper and measure out all of the ingredients at this point.
In a large bowl, put the softened butter and both sugars and beat until soft and creamed. Add the vanilla extract and the egg.
Sieve the flour into the bowl then and add the bicarbonate of soda and salt. Mix well with a wooden spoon and add both sets of the chocolate chips.
Place each spoonful of the mixture onto the greaseproof paper, there should be enough for about 12 cookies and ensure you leave enough space to allow the mixture to spread out.
Bake in the oven for 10 minutes until slightly browned on the sides and still soft in the middle.
Leave the cookies to stand for a few minutes to harden slightly and then move over to a cooling rack.
Recipe by Food & Fitness Always at https://foodandfitnessalways.com/chewy-chocolate-chip-cookies-1216/