Cook sweet potatoes. You can peel, cut into pieces, and boil them until tender. Or prick holes all over with a fork and bake them at 450°F for about 45 minutes. Sweet potatoes should pierce easily with a fork when done. Allow to cool for about 30 minutes or until they can be handled. For roasted sweet potatoes, slice in half and scoop out the flesh with a spoon. Discard the skin.TIP - We like to cool down the cooked sweet potatoes before adding with the other ingredients - both to make it easier to handle them while scooping out the flesh, but also to ensure that the hot potatoes don’t start cooking the eggs into scrambled eggs before baking the souffle.
In a large bowl or in the bowl of a food processor/blender, add all remaining ingredients for the souffle filling. Mash or puree until desired texture.
Spread sweet potato mixture in a 2 quart baking dish.
Prepare the streusel topping by whisking together the brown sugar, flour, cinnamon, salt, and pecans.
Cut pieces of butter into the mixture and work together with your fingers to make a sand-like crumble.
Sprinkle the crumble over the top of the sweet potatoes in the baking dish.
Bake for 40-45 minutes, until the topping is golden brown and toasted. The souffle will puff slightly although it’s more difficult to see under the crumb topping. The puff should be uniform across the top of the souffle (if it’s puffed just around the edges, bake 5-10 more minutes so the center cooks as well.) Cover the top with aluminum foil, if needed, to prevent over-browning of the crumb topping.
Notes
Although it's possible to use canned sweet potatoes over fresh for this recipe, I highly recommend sticking to fresh. Baking or boiling fresh sweet potatoes lends so much more flavor compared to the canned variety. If you do substitute with canned, simply mash and strain them of as much liquid as possible.
It is best to use fresh, medium-sized sweet potatoes for this recipe. Choose sweet potatoes that are firm with smooth skin.
You can substitute the heavy cream for half and half or whole milk.
Room temperature eggs will incorporate more air during blending and provide more lift to the cooked souffle.
The texture is a personal preference. If you blend the mixture, as we did here, you will get a little more lift to the souffle (though not a lot like a traditional souffle) and the base will be very smooth. Mash with a potato masher/mix by hand for a little more texture in the sweet potatoes. Some people also use a hand mixer.