- For cake:
- 3/4 cup unsalted butter, softened, plus additional for greasing bundt pan
- 2 1/4 cups all-purpose flour plus additional for dusting pan
- 2 teaspoons baking powder
- 1 teaspoon baking soda
- 1 teaspoon cinnamon
- 3/4 teaspoon ground allspice
- 1/2 teaspoon salt
- 1 1/4 cups canned solid-pack pumpkin (not pie filling)
- 3/4 cup well-shaken buttermilk
- 1 teaspoon vanilla
- 1 1/4 cups granulated sugar
- 3 large eggs
- For icing:
- 8 teaspoons well-shaken buttermilk, plus
- 1 1/2 cups confectioners' sugar
- Make cake: Put oven rack in middle position and preheat oven to 350 degrees F. Butter bundt pan generously, then dust with flour, knocking out excess.
- Whisk together flour (2 1/4 cups), baking powder, baking soda, cinnamon, allspice, and salt in a bowl. Whisk together pumpkin, 3/4 cup buttermilk, and vanilla in another bowl.
- Beat butter and granulated sugar in a large bowl with an electric mixer at medium-high speed until pale and fluffy, 3 to 5 minutes, then add eggs and beat 1 minute. Reduce speed to low and add flour and pumpkin mixtures alternately in batches, beginning and ending with flour mixture and mixing until batter is just smooth.
- Spoon batter into pan, smoothing top, then bake until a wooden pick or skewer inserted in center of cake comes out clean, 45 to 50 minutes. Cool cake in pan on a rack 15 minutes, then invert rack over cake and reinvert cake onto rack. Cool 10 minutes more.
- Make icing: While cake is cooling, whisk together buttermilk and confectioners sugar until smooth. Drizzle icing over warm cake, then cool cake completely. Icing will harden slightly.