For Streusel Topping: Cream together all ingredients until crumbly For Cream: Put cream, vanilla beans, and vanilla extract in large pot and bring just to a boil. In separate bowl, mix egg yolks, eggs, cornstarch, and sugar together. Temper hot cream into eggs until fully mixed. Return to pot and stir continuously over low to medium heat until custard consistency achieved. Be careful because once it starts to thicken it moves quickly. Add butter at end (sometimes I forget this step and it doesn't seem to make a big difference). Both parts can be made ahead. When ready to make,thinly slice bananas in bottom of ramekin (a/b 1/2 to 3/4 banana per person). Scoop cream over bananas and top with crumble. Bake 15-20 minutes until lightly browned on top and bubbly. Let rest 10 minutes before serving as it will be very hot.