For the sweet potatoes: Heat the oven to 350 degrees F. Place the potatoes on a rimmed baking sheet and bake until tender when pierced with the point of a paring knife, about 1 hour.
Cool the potatoes slightly. Peel the potatoes, discard the skins, and place them in a medium bowl. Mash with a potato masher or large fork until smooth. Stir in the eggs, milk, brown sugar, melted butter and vanilla until combined; season with salt and pepper.
Meanwhile, for the topping: Combine the pecans, brown sugar, flour and butter in the bowl of a food processor fitted with the blade attachment. Pulse until combined. Set aside.
Transfer the sweet potato mixture to a medium casserole dish and sprinkle with the topping. Place the casserole in the oven and bake until bubbly and browned on top, about 30 minutes. Serve immediately.
Recipe courtesy of Virginia Willis