Pumpkin and sweet potato puree with orange and thyme served in a pumpkin shell

This is a new recipe I am trying for the holidays from Fine Cooking Magazine.  I love the way it is served in the pumpkin shell.  I think the leftovers would be great mixed with a little chicken broth or half and half for a soup.  Mmmmmmm..

2 T. butter
2 Sugar Pie pumpkins
4 sweet potatoes
2 T. brown sugar
2 T. grated orange zest
1 t. thyme

Preheat oven to 350.  Put aluminum foil in a 13 x 9 pan.  Cut all the sweet potatoes and one of the pumpkins in half and place cut side down in pan.  Cover with foil and bake for one and a half hours.
In the oven at the same time,  bake the other pumpkin, with just the top cut off. 
Clean seeds and stringy pulp from pumpkins.  Scoop pumpkin out of shells..leaving about 1/4 " in the whole pumpkin.  Puree. Peel sweet potato, then puree.  Mix with pumpkin puree, butter, brown sugar, zest and thyme.  Put this mixture into the whole pumpkin shell.  Put the pumpkin on a baking sheet and bake at 350 for 40 minutes.