* Approximately 3 medium bananas should yield the 1 cup of mashed ~-----------------------------------------------------~---------------CRUST: Preheat the oven to 180ºC . Place the crumbs in a mixing bowl and add the butter and sugar. Blend well. Press the crumb mixture onto the bottom and partly up the sides of a greased 23 cm springform pan. Smooth the crumb mixture along the bottom to an even thickness. Bake for about 10 minutes in the oven at 180ºC . Cool before filling. CHEESECAKE: Preheat the oven to 180ºC . In a large mixing bowl, beat the cream cheese, sugar and lemon juice together. Add the eggs, one at a time, beating well after each addition. Stir in the sour cream and the mashed bananas and blend well until very smooth. Pour the mixture into the prepared crust and bake for 1 hour. Cool in the oven, with the door propped open, until the cake is at room temperature. Chill until serving time.