In a large bowl, add the soft butter, caster sugar and Muscovado sugar.
Using the beater attachments, gently start the Hand Mixer at speed 1, and beat the butter with sugar until the mixture is pale and fluffy.
Add the vanilla extract and mix to combine.
Add the eggs and baking powder. Once mixed, pour in the flour, beating to create a smooth mix.
Once smooth and creamy, add the chocolate chips. Gently stir with a spoon to incorporate.