Sweet Potato Spice Cake with Fresh Ginger & Pecan Streusel Topping
This cake is incredibly moist, thanks to the sweet potato, and the fresh ginger adds a vibrancy that other spice cakes can only dream of. One piece is never enough.
Baking and mashing a sweet potato is easy. Heat the oven to 450°F. Prick the skin of the sweet potato several times with a fork, set the potato directly on the oven rack, and bake until very tender, about 1 hour. (If you’re in a hurry, prick a large sweet potato with a fork, set on a paper towel, and microwave on high until tender, about 5 minutes.) When the potato is cool enough to handle, peel off the skin and smash the flesh in a bowl with a masher, or whisk until smooth.
Make the pecan streusel topping:
In a small bowl, stir the flour, brown sugar, pecans, and salt. Drizzle the melted butter over the dry ingredients and stir until well combined. The streusel should feel clumpy, not sandy, when gently squeezed between your finger- tips. If the streusel seems dry, add more melted butter.
Make the cake:
Position a rack in the center of the oven and heat the oven to 350°F. Lightly oil and flour a 9-inch-square baking pan; tap out excess flour.
In a medium bowl, combine the oil, brown sugar, and eggs and, using a whisk, stir until the mixture is smooth and the sugar begins to dissolve, 30 to 60 seconds. If the sugar forms lumps, break them up with your fingers; a few tiny lumps are fine. Whisk in the sweet potato, molasses, grated ginger, salt, cinnamon, cardamom, and nutmeg. Sift the flour and baking soda directly onto the batter. Using a whisk or rubber spatula, combine the ingredients until well blended and almost smooth.
Pour the batter into the prepared pan, spreading it evenly with the spatula. Sprinkle the streusel evenly over the batter, creating small clumps as you go by squeezing the streusel between your fingers. Bake until a skewer inserted in the center comes out with only moist crumbs clinging to it, about 45 min. Set the pan on a rack to cool for 15 min. Run a knife around the edge of the pan. Let cool until just warm and then cut into squares and serve from the pan, or wrap well in plastic. Store at room temperature for up to a week.