Start by preheating your oven to 400°F (200°C). Line a rimmed baking sheet with foil for effortless cleanup.
Gently pierce each sweet potato a couple of times. Place them on the prepared baking sheet and roast until they're incredibly soft and cooked through, about 60-75 minutes. Once done, reduce your oven temperature to 350°F (175°C).
Carefully peel the cooled, tender sweet potatoes (the skin should practically fall off!) and transfer the smooth flesh into a large mixing bowl.
Mash the potatoes thoroughly until they're nice and smooth. Let them cool for about 5-10 minutes to ensure the eggs don't cook prematurely when added.
Now, stir in the 1/2 cup brown sugar, 1/2 cup melted butter, milk, eggs, vanilla extract, and season with salt and pepper. Use an electric hand mixer to blend the mixture until it's beautifully combined and creamy.
Pour this luscious sweet potato mixture into a lightly greased casserole dish (around 12x8 inches works perfectly) and spread it out evenly. Set it aside for a moment.
Time for the irresistible pecan topping! In a separate medium mixing bowl, use a fork to combine the flour, 1/2 cup brown sugar, cinnamon, and pecans. Use your fingertips to break up any stubborn brown sugar clumps.
Add the 1/4 cup melted butter to the topping mixture and stir it well until it's evenly moistened and crumbly. Don't worry if it seems a bit dry at first – just keep tossing!
Generously sprinkle this delightful pecan topping evenly over the sweet potato mixture in your casserole dish.
Bake in your preheated 350°F oven for about 40 minutes, or until the casserole is bubbly and heated through, and the topping is golden brown. If the topping starts to get too dark, simply tent it loosely with foil during the last 10 minutes. Serve warm and savor every healthy, delicious bite!