Pre-heat the oven to 180°c / 350°f / Gas Mark 4. Cover the baking tray with baking paper. In the mixing bowl, cream together the butter, lard and sugar until light and fluffy.
Add the egg and vanilla and beat well. Stir in the flour, ensuring that mixture is smooth but stiff. Pour some desiccated coconut into the shallow dish.
Roll the biscuit mixture into balls approximately 1¼"/3cm. Toss balls in desiccated coconut and coat well. Place on baking paper and press gently on top to flatten slightly.
Press a chocolate button into the top of each. Bake in the centre of the oven for 10-15 minutes or until golden brown. Remove from oven and cool on a wire rack. Store in an airtight container.