Sweet Potato Pie with Toasted Marshmallow & Pecan Streusel

Steps

1. Roast the sweet potatoes: Heat the oven to 400°F with a rack in the center. Prick the sweet potatoes all over with a fork and set them on a foil-lined rimmed baking sheet. Roast until completely tender and easily pierced with a knife, 50 to 55 minutes. Cool until you can handle them, then halve lengthwise, scoop out the flesh, and mash until smooth — you want 2 cups (450g). Cool to room temperature. (This can be done up to 3 days ahead; refrigerate the mash.)
2. Make the crust: Pulse the flour, sugar, and salt in a food processor to combine. Add the cold butter and pulse in 1-second bursts until the mixture looks like coarse meal with some pea-sized pieces, 8 to 10 pulses. Drizzle in 4 tablespoons of ice water and pulse just until the dough clumps when squeezed, adding up to 2 more tablespoons only if it stays dry and crumbly. Turn out onto plastic wrap, press into a flat disk, wrap, and refrigerate at least 1 hour (or up to 2 days).
3. Roll and fit: On a lightly floured surface, roll the chilled dough into a 12-inch circle about ⅛-inch thick. Ease it into a 9-inch pie plate without stretching, trim the overhang to 1 inch, tuck it under to form a thick rim, and crimp decoratively. Freeze for 20 to 30 minutes, or refrigerate for 1 hour, until the dough is firm.
4. Blind-bake the crust: Heat the oven to 375°F with a rack in the lower third. Line the chilled crust with parchment paper or foil and fill with pie weights or dried beans. Bake for 20 minutes, then lift out the weights and parchment and prick the bottom all over with a fork so the base doesn't puff. Return to the oven and bake until the bottom is dry and just beginning to turn pale gold, 5 to 7 minutes more. Cool the crust slightly and reduce the oven to 350°F.
5. Make the custard: In a large bowl, whisk the eggs and the extra yolk just until uniform with no streaks of white — do not beat to a foam. Whisk in the brown sugar, granulated sugar, cinnamon, nutmeg, ginger, cloves, and salt, then whisk in the mashed sweet potatoes until completely smooth. Whisk in the evaporated milk and vanilla, then whisk in the melted, slightly cooled butter in a slow stream so it doesn't scramble the eggs.
6. Fill the pie: Pour the custard into the blind-baked crust and smooth the top. Set the pie on a baking sheet and bake at 350°F for 35 minutes.
7. Make the streusel: While the pie bakes, stir together the chopped pecans, brown sugar, flour, cinnamon, and salt in a small bowl. Work in the cold butter with your fingertips until the mixture clumps into sandy, pea-sized crumbles.
8. Add the streusel and finish baking: After the first 35 minutes, sprinkle the streusel evenly over the partly set custard. Continue baking for 15 to 20 minutes more, until the edges are set and puffed while the very center still wobbles as one unit when you nudge the pan — a sloshy center needs more time. The filling should read about 175°F in the center, well past the 160°F where eggs are fully cooked. If the crust rim darkens too fast, tent it loosely with foil for the last 15 minutes.
9. Cool: Cool the pie completely on a wire rack, at least 2 hours — the custard finishes setting as it cools, and slicing too soon makes it run.
10. Toast the marshmallows: Just before serving, mound the mini marshmallows over the top of the pie. Broil on a rack about 6 inches from the heat until the marshmallows are puffed and deeply golden, 1 to 2 minutes, rotating the pie once — watch constantly, they go from golden to burnt in seconds. Cool for 5 minutes, then slice and serve.