Preheat oven to 180C. Melt the chocolate and set aside to cool. Using an electric mixer, cream the butter and gradually beat in the brown sugar until light and fluffy. Beat in the egg and when well mixed beat in the melted chocolate.
Next sift the flour with the salt and fold into creamed mixture with the buttermilk, vanilla and choc bits.
Divide the batter among 12 greased muffin tins. Bake in the preheated oven for about 30 mins or until an inserted skewer comes out clean.
Let muffins cool in the tin before turning out on to a wire rack to cool completely.
