01 -
Preheat the oven to 350°F (175°C) and grease a baking pan.
02 -
Whisk together all-purpose flour, baking powder, baking soda, salt, and ground cinnamon in a bowl.
03 -
In a separate bowl, blend mashed sweet potatoes, granulated sugar, brown sugar, vegetable oil, eggs, and vanilla extract until smooth.
04 -
Alternately add the dry mixture and buttermilk to the wet mixture, stirring gently until just combined.
05 -
Pour half the batter into the prepared pan. Mix brown sugar and ground cinnamon, then sprinkle evenly over the batter.
06 -
Pour the remaining batter over the cinnamon layer and gently swirl with a knife to combine.
07 -
Bake for 35 to 40 minutes, or until a toothpick inserted in the center comes out clean.
08 -
Allow the cake to cool slightly in the pan before glazing.
09 -
Whisk powdered sugar, milk, and vanilla extract until the glaze is smooth.
10 -
Drizzle the glaze evenly over the warm cake before serving.