Notes: Choose sweet potatoes with dark red skin and bright orange flesh, often sold as Garnet yams, for this moist pound cake. You can make the sweet potato purée (step 1) up to 2 days ahead; cover and chill. You can bake the cake up to 1 day ahead; wrap tightly and store at room temperature. Serve with scoops of butterscotch ice cream.
1 1/4 pounds Garnet sweet potatoes (see notes)
3/4 cup (3/8 lb.) butter, at room temperature
1 1/4 cups sugar
3 large eggs
1 tablespoon grated orange peel
1 1/2 teaspoons vanilla
1 3/4 cups all-purpose flour
1 1/2 teaspoons baking powder
1/4 teaspoon mace
1/4 teaspoon salt
How to Make It
Prick sweet potatoes several times with a sharp knife. Place on a 12- by 15-inch baking sheet and bake in a 375° regular or convection oven until very soft when pierced, about 40 minutes. When cool enough to handle, peel sweet potatoes and whirl in a blender or food processor until smooth. You will need 1 cup purée; save any extra for other uses.
In a large bowl, with a mixer on medium speed, beat butter and sugar until well blended. Add eggs one at a time, beating to blend after each addition. Beat in 1 cup sweet potato purée, the orange peel, and the vanilla.
In another bowl, mix flour with baking powder, mace, and salt. Add the flour mixture to batter; mix on low to incorporate dry ingredients, then beat at medium speed until well blended.
Scrape batter into a buttered 4 1/2- by 8 1/2-inch loaf pan.
Bake in a 350° regular or 325º convection oven until a wooden skewer inserted into the center comes out clean, 1 hour to 1 hour 15 minutes. Cool in pan on a rack about 15 minutes. Invert cake onto a plate and cool completely, about 1 hour. Cut into 1/2-inch slices and serve, or wrap tightly and store at room temperature.