All you do is sift the flour and baking powder into a roomy bowl, lifting the sieve quite high to give the flour a good airing as it goes down, then simply add all the other ingredients (except the pears).
Now, using an electric hand whisk, combine them for about 1 minute until you have a smooth creamy consistency. Next spoon the mixture into the prepared tin, and level off using the back of a tablespoon.
Now arrange the pears in a circle on top (a few can go in the middle).
To make the topping, mix the flour and sugar in a bowl then add the melted butter and lightly crumble it with a fork. After that stir in the nuts, sprinkle the mixture all over the pears and bake near the centre of the oven for 45 minutes.
Leave it to cool in the tin for 20 minutes before loosening the edge with a palette knife.
Then place the tin on an upturned bowl and carefully slide the tin downwards. After that use the palette knife to slide the cake off its liner onto a wire cooling rack.
Just before serving, dust the surface with icing sugar.