In a small bowl, mix together the flour, brown sugar, cinnamon, and chopped pecans. Drizzle the melted butter over this mixture. Stir until everything is combined well. Set this bowl aside.

Boil: Take the peeled and diced sweet potatoes and place them in a large pot. Cover with water, add a pinch of salt, and bring to a boil. Cook for about 15 to 25 minutes, or until soft. Drain the sweet potatoes.

Roast: Preheat your oven to 425°F (220°C). Poke holes in whole sweet potatoes, wrap in foil, and roast for 40 to 55 minutes, or until tender. Let them cool slightly and scoop out the flesh.

Preheat your oven to 350°F (175°C). In a large mixing bowl, mash the cooked sweet potatoes until smooth. Add the light brown sugar, melted butter, eggnog, room-temperature eggs, vanilla extract, cinnamon, nutmeg, and kosher salt. Mix until fully combined.

Pour the sweet potato mixture into a greased baking dish. Sprinkle the pecan topping evenly over the sweet potato mixture. Bake for about 30 minutes, or until the top is golden brown.