Preheat oven to 180C.
Peel and slice nashi into 4 thick round circles. Set aside. Finely dice the remaining nashi.
Put sugar and water into a small saucepan and heat until sugar is dissolved and has turned a light caramel colour. Pour a little into the base of four large greased non- stick muffin tins. Arrange the nashi slices on top of the caramel.
Melt the butter and leave to cool. Beat eggs with vanilla and brown sugar. Add butter. Sift the flour and stir well to combine. Fold in the extra diced nashi. Divide the mixture between the muffin tins.
Bake for 20-30 minutes until set.
Remove from oven and turn out onto plates.
Serve warm with extra caramel sauce and cream or icecream.