
2 cups (9 oz) all-purpose flour
1 cup (4.5 oz) chestnut flour
½ tsp baking powder
½ tsp baking soda
½ tsp salt
4 large eggs, at room temperature
½ lb. (2 sticks) unsalted butter, softened
2 cups sugar
2/3 cup butter milk, at room temperature
1/3 cup rum
1 ½ cups (6oz) coarsely chopped nuts (optional)
Preheat the oven to 325 °F. Spray the pans with vegetable oil spray. (Or line the loaf pans with parchment paper.)
In a large bowl, mix the flours, baking powder, soda, and salt together, then sift the mixture three times. In a small bowl, whisk the eggs with a fork to combine the whites and yolks; set aside.
In a bowl of a stand mixer (use the paddle attachment) or another large bowl, beat the butter for a few seconds until creamy. Add the sugar in a steady stream and beat at medium speed (high-speed with a hand mixer) until light and fluffy, about 4 minutes. Beating constantly, dribble the eggs into the butter mixture a little bit at a time, taking 2 to 3 minutes to add them all.
Stop the mixer and add one-third of the flour mixture and beat on low speed only until no flour is visible. Stop the mixer and add half of the buttermilk and half of the rum and beat only until the liquid is absorbed. Repeat with half of the remaining flour, then all of the remaining buttermilk and rum, and finally the remaining flour with the walnuts if using. Scrape the batter into the prepared pan(s). Bake until a toothpick inserted in the center of the cake comes out clean, about 40 minutes for a tube pan or 50 to 55 minutes for the loaves. Cool in the pan(s) on a rack for about 10 minute before unmolding.
Could substitute glazed sweet chestnuts in batter