Preheat the oven to 400 degrees F.

Prick the sweet potatoes all over with a fork and put them on a roasting pan.

On another roasting pan prick bananas and lay out in a single layer.

Roast sweet potatoes for 45 minutes until very soft and roast bananas for 25 minutes. (If you are in a huge hurry, you can boil the sweet potatoes, but do not try boiling the bananas!)

Remove both pans from the oven and allow to cool slightly.  

In a small sauce pot heat cream with bay leaf until reduced by half, then keep warm until ready to puree potatoes and bananas. 

When the potatoes are cool enough to handle, scoop out the flesh into the bowl of a food processor (A blender will work, but only if the potatoes are cool).

Add peeled bananas. Season with salt, add butter, cream (make sure you took the bay leaves out!), cinnamon, nutmeg, vanilla and puree until smooth (or if you like it a little chunky, a little chunky).

Pour into an oven-proof dish. 

Make the topping by combining flour, cold butter and brown sugar in the food processor and pulse until you have the texture of coarse bread crumbs.

Sprinkle on top of the puree and place under the broiler until golden brown and crispy, about 4-5 minutes.