01 -
Preheat the oven to 350°F. Grease a 9×5-inch loaf pan with butter or nonstick spray.
02 -
In a medium bowl, whisk together the flour, baking soda, and salt. Set aside.
03 -
In a large bowl, beat the butter and granulated sugar with an electric mixer on medium speed until light and fluffy, about 2 minutes.
04 -
Beat in the eggs one at a time, then mix in the vanilla.
05 -
With the mixer on low speed, mix in a third of the flour mixture, followed by half of the buttermilk. Repeat, alternating between the flour and buttermilk, ending with the flour. Mix just until incorporated.
06 -
In a small bowl, combine the brown sugar and cinnamon.
07 -
Pour half of the batter into the prepared loaf pan and smooth the top. Sprinkle evenly with half of the cinnamon-sugar mixture. Pour the remaining batter on top and spread evenly. Sprinkle with the remaining cinnamon sugar.
08 -
Using a butter knife, swirl the batter a few times to create a marbled effect. Don’t overmix.
09 -
Bake for 50-60 minutes, until a toothpick inserted into the center comes out clean. Let cool in the pan for 10 minutes before removing to a wire rack to cool completely.