Because this side dish is served in a tart shell it is fairly substantial and could stand as a main course for the vegetarians at your table.
The dish can be assembled a day and reheated just before serving in a 300 degree oven for about 20 minutes.
30 minutes preparation time, plus 1 hour to prepare and pre-bake the tart crust
30 minutes baking time
1 Pre-Baked Tart Crust
2 large sweet potatoes
1 teaspoon nutmeg
1/2 cup cream
8 ounces (2 cups) cranberries
1/4 cup granulated sugar
1 teaspoon lemon zest
salt and pepper
Prepare and prebake the tart shell according to these instructions. Slide the tart pan onto a cookie sheet and preheat oven to 350 degrees.
Peel the sweet potatoes and cut them into large chunks. Put them in a medium stockpot with a few shakes of salt and cover with water. Bring to a boil and simmer until the sweet potatoes are soft, about 20 minutes. Reserve about 1/2 cup of the cooking water and drain off the remaining water.
Turn the potatoes into the bowl of a food processor, add the cream, and blend until smooth. If needed to make the sweet potatoes smooth, add some of the reserved cooking water a splash at a time. Taste and add additional salt and pepper if needed.
In another stockpot, add the cranberries, about a cup of water, the sugar, and the lemon zest. Cover the pot and bring it to a simmer. Keep it covered because as the cranberries cook, they will pop open and you don't want them flying all over your kitchen. Simmer until the cranberries have all popped open and are soft, about 20 minutes. Mash them with a potato masher until the mixture is the texture of a fruit jam. If it is too thin, let it simmer for a few more minutes uncovered.
After the tart shell has baked, smooth just over half of the sweet potato mixture over the bottom of the shell, reserving the remaining sweet potato. Next add a layer of the cranberry sauce, spreading it evenly across the top of the sweet potato. There may be more than you need. Reserve a few tablespoons of the cranberry mixture to put on top of the last layer.
Layer the remaining sweet potato on top of the cranberry layer. Don't worry about spreading the layer too evenly; it looks pretty to have some of the cranberry sauce peeking through. Add a few dollops of the remaining cranberry mixture for color.
Bake the tart until it heats through, about 30 minutes. Remove from the oven and let rest for a few minutes before serving.