Sweet Potato Soufflé with Spiced Pecan Topping

INGREDIENTS

• 4 large sweet potatoes, about 3 1/2 lb. total
• Unsalted butter for baking dish, plus 4 Tbs. (1/2 stick) butter, melted
• 4 eggs
• 1/2 cup evaporated milk
• 1/2 tsp. ground cinnamon
• Kosher salt, to taste
• 1/2 cup all-purpose flour
• 1/4 cup firmly packed light brown sugar
• 1 tsp. ground cinnamon
• 1 tsp. galangal powder or ground ginger
• 1/2 tsp. ground vanilla bean
• Pinch of kosher salt
• 6 Tbs. (3/4 stick) cold unsalted butter, cut into 1/4-inch dice
• 8 oz. pecans, roughly chopped