01 -
Preheat the oven to 175°C. Generously grease a 10-cup Bundt pan with butter or baking spray, ensuring all surfaces are thoroughly coated.
02 -
In a medium bowl, whisk together all-purpose flour, baking powder, baking soda, salt, and 1 teaspoon ground cinnamon until homogenized.
03 -
In a large mixing bowl, beat softened butter and granulated sugar on medium speed for 3 to 4 minutes until the mixture is light and fluffy. Incorporate eggs one at a time, mixing thoroughly after each addition, then blend in vanilla extract.
04 -
Alternately add one third of the flour mixture to the batter, followed by half the sour cream. Repeat the process, alternating flour and sour cream, finishing with the remaining flour mixture. Mix just until combined; avoid overmixing.
05 -
In a small bowl, mix packed brown sugar with 1 tablespoon ground cinnamon until uniform.
06 -
Pour half of the batter evenly into the prepared Bundt pan. Sprinkle with half the cinnamon-sugar mixture. Layer the remaining batter on top and finish with the rest of the cinnamon-sugar. Gently swirl through the layers with a knife using 3 to 4 figure-eight motions for a marbled effect.
07 -
Place pan in the center of the oven and bake for 45 to 55 minutes, or until a toothpick inserted in the center emerges clean. Cool in the pan for 10 minutes, then carefully invert onto a wire rack.
08 -
Allow the cake to cool completely before dusting evenly with powdered sugar. Slice and serve.