Lightly butter and base line a 20cm round cake tin - I use one with a spring clip removable base.
Mix 25g of the butter with 25g of the sugar to a cream and spread on the base of the tin. Sprinkle about 1/4 of the chopped ginger onto the base and place pears down onto this.
For the cake, combine the White Mix, baking powder, spices and the remaining stem ginger, butter and sugar along with the eggs. (I mixed with a wooden spoon until blended but I am sure you could use a hand mixer - not sure if this would break up the chopped ginger so have only ever used the hand method).
Pour this over the pears and bake for around 35 mins.
Leave it to cool for 10-20 mins then pop a plate on top and turn upside down.
You can leave until it is cold to eat but truly scrumptious when warm.