Preheat your oven to 350°F (175°C) and grease a 2-quart baking dish.

Cook sweet potatoes until tender. Boil for 20 minutes or bake at 400°F for 45–60 minutes, then cool, peel, and mash until smooth.

Combine mashed sweet potatoes with melted butter, sugars, egg yolks, cream, vanilla, spices, and salt. Mix until smooth.

Whisk egg whites in a clean bowl until soft peaks form, approximately 3–5 minutes.

Fold beaten egg whites into the sweet potato mixture gently.

In a separate bowl, mix pecans, flour, and sugar, then incorporate cold butter until crumbly.

Pour sweet potato mixture into the baking dish and sprinkle with pecan topping. Bake for 35–40 minutes.

Let the soufflé cool slightly before serving hot.