Pecan-Crusted Sweet Potato Pound Cake

To roast the sweet potatoes: Preheat the oven to 400°F with a rack in the center. Line a baking sheet with parchment or foil. Use a paring knife or fork to pierce the sweet potatoes several times each. Bake the sweet potatoes for 45 to 60 minutes, or until tender. Carefully slice the baked potatoes in half lengthwise and spread them open to allow them to cool slightly at room temperature.    , To prepare the pecan crust: Reduce the oven temperature to 350°F. Grease a tube pan with a capacity of at least 8 cups or line and grease an 8" square pan. Scatter 3/4 cup (85g) of the pecans evenly in the bottom of the pan. Sprinkle 2 tablespoons (26g) of the brown sugar evenly over the top. , To finish the sweet potato purée: Remove the skins of the sweet potatoes and transfer 1 1/3 cups (319g) of the flesh to the bowl of a food processor. Add the buttermilk and mix until a smooth purée forms, about a minute. Pause the food processor and scrape the inside of the bowl to ensure the ingredients are fully combined. Set the purée aside. (The sweet potato purée can be made and refrigerated up to 4 days in advance.) , To make the cake batter: In a medium bowl, combine the flour, baking powder, salt, baking soda, cinnamon, and nutmeg., In a large bowl or bowl of a stand mixer fitted with the flat beater, beat the butter and sugars at medium speed until fluffy, 1 to 2 minutes. , Mix in the eggs one at a time on medium speed, scraping the bowl after each addition. Mix in the vanilla until combined. , Add the sweet potato purée and mix on medium speed until combined, about 30 seconds. Scrape the bowl. , Add the dry ingredients and beat on medium speed, stopping to scrape down the bowl as needed, until a very thick batter forms, about 2 minutes. , To assemble the cake: Transfer the batter to the prepared pan and spread it into an even layer. , In a small bowl, combine the remaining pecans and brown sugar with the maple syrup. Scatter evenly over the top of the cake batter.  , Bake the sweet potato pound cake for 60 to 65 minutes for the tube pan or 70 to 75 minutes for the 8" square pan, or until a skewer or paring knife inserted into the center comes out clean or with a few moist crumbs attached. , Remove the sweet potato pound cake from the oven and let it cool in the pan for 15 minutes. Once it has cooled slightly, invert it onto a wire rack to cool completely. Before slicing and serving, dust the surface of the cake with Snow White Non-Melting Sugar or confectioners’ sugar. , Storage information: Store leftover sweet potato pound cake in an airtight container at room temperature for up to 4 days.