Place the 50g butter and 100g brown sugar into the Thermomix for 4 minutes at 100 on speed 1 (so its nice and bubbly).Pour into a 22cm tin with baking paper on the bottom, then place the pears onto the caramel in a circular pattern.Beat the butter and sugar for 2 minutes on Speed 5 til light and fluffy. Add the eggs one at a time, through the hole in the lid, beating for about 30 seconds after each addition. Then add the ginger, and then the flour and baking powder. Turn on to speed 4 and the moment you see (by looking through the hole in the lid) that the flour is combined turn it off. Spoon over pears carefully to not disturb the pattern.Bake in a pre heated 180 degree oven for 40 minutes or until a skewer comes out clean. Rest for 5 minutes then invert on to a serving plate, and serve warm or at room temperature.