Instructions

1. Arrange a rack in the lower third of the oven and heat the oven to 400ºF. Line a rimmed baking sheet with aluminum foil.
2. Poke 5 pounds sweet potatoes several times with a fork and space on the baking sheet, arranging them evenly apart. Bake until fork-tender and they can be easily squeezed with tongs, 1 to 1 1/2 hours. Let sit until cool enough to handle, at least 20 minutes.
3. Meanwhile, reduce the oven temperature to 375ºF. Coat a 9x13-inch baking dish with cooking spray. Make the pecan topping.
4. Whisk 1 1/2 cups all-purpose flour, 1/2 cup packed dark brown sugar, 1/4 cup granulated sugar, and 1/2 teaspoon kosher salt together in a medium bowl until combined. Stir in 1 cup coarsely chopped pecans. Stir in 10 tablespoons melted unsalted butter until evenly moistened.
5. Split the sweet potatoes lengthwise. Scoop out the flesh with a large spoon into a large bowl; discard the peels. Mash the sweet potato flesh with a potato masher until smooth (about 5 cups).
6. Whisk 1 cup half-and-half and 2 large eggs together in a medium bowl with a fork until combined. Add to the sweet potato and stir with a flexible spatula until combined. Stir in 6 tablespoons melted unsalted butter, 1/3 cup granulated sugar, 1 tablespoon lemon juice, 1 tablespoon vanilla extract, 1 1/2 teaspoons ground cinnamon, and 1 teaspoon kosher salt. Transfer to the baking dish and spread into an even layer.
7. Using your hands, clump and break the topping into pea-size pieces and sprinkle evenly over sweet potato mixture. Bake until the topping is deep golden-brown and the filling is warmed through, about 40 minutes.