Aside from the obvious link between October and pumpkin season, there's another great reason for slipping some pumpkin into your baked goods this year. It's extremely low in calories, and canned pumpkin can act as the "fat" in many recipes, replacing butter and oil. Try making boxed brownies with pumpkin: to one box of store bought brownie mix, add a can of pumpkin and nothing else, and bake as directed on the box. Bet you'll never know the difference.
Of course, when you slather a pumpkin buttercream over the cake, you've pretty much negated any benefits to replacing butter and oil with pumpkin inside the cake, but outside of this lovely season, how many other times of the year do you really feel like digging into pumpkin anything?
Ah, autumn. The great justifier in orange sweets.
For the cake, you will need:
1/2 cup (1 stick) unsalted butter, softened
1 cup firmly packed light brown sugar
1/2 cup granulated sugar
1 large egg
1 cup buttermilk
1 teaspoon vanilla extract
1 1/2 cups all-purpose flour
3/4 cup Dutch cocoa powder
1/4 teaspoon baking soda
1/2 teaspoon baking powder
1/4 teaspoon salt
1 14-ounce can pure pumpkin (not pumpkin pie filling), 2 tablespoons reserved for buttercream
1 tablespoon pumpkin pie spice
For the pumpkin buttercream:
2 sticks unsalted butter, softened
2 tablespoons canned pumpkin
1/4 teaspoon pumpkin pie spice
5 cups powdered sugar
4 tablespoons milk
Preheat the oven to 325°F. Butter and lightly flour a 9×5x3-inch loaf pan.
In the bowl of a stand mixer on medium speed (or in a large bowl if using a hand mixer), cream the butter until smooth. Add the sugars and beat until fluffy, about 3 minutes. Add the egg and beat well, then the buttermilk and vanilla. Sift the flour, cocoa, baking soda, baking powder and salt together and add to wet ingredients. Stir pumpkin in with a spoon until well-blended, but do not overmix.
Pour the batter into the prepared loaf pan. Bake for 60 to 70 minutes, or until a cake tester inserted into the center of the loaf comes out clean. Cool in pan on a rack for about 10 to 15 minutes, then flip onto a plate for further cooling.
While cake is cooling, prepare buttercream. Cream butter in a bowl until smooth on medium speed. Turn off mixer and add half of powdered sugar. Turn mixer on lowest speed to combine (otherwise powdered sugar will fly all over your kitchen). Turn mixer off and add second half of sugar, beating on low until combined. Add vanilla and milk and mix on low speed until completely combined. Stir pumpkin and pie spice in with a spoon until blended.
Once cake is completely cooled, spread buttercream on thick with an offset spatula or butter knife. Serve immediately or refrigerate.
