Prepare the Pan & OvenPreheat your oven to 350°F (175°C). Grease and flour a bundt pan thoroughly, making sure every groove is coated to prevent sticking.
Mix the Dry IngredientsIn a medium bowl, whisk together the flour, baking powder, and salt. Set aside.
Cream Butter & SugarIn a large mixing bowl, beat the softened butter and granulated sugar together until light and fluffy, about 3–4 minutes. This step creates air pockets that give the cake a tender crumb.
Add Eggs, Sour Cream & VanillaBeat in the eggs one at a time, mixing well after each addition. Stir in the sour cream and vanilla extract until combined
Incorporate the Dry Mix & MilkAlternate adding the dry ingredients and milk to the butter mixture, starting and ending with the dry ingredients. Mix until just combined — overmixing can make the cake dense.
Assemble the SwirlIn a small bowl, mix the brown sugar and cinnamon. Pour half of the cake batter into the prepared bundt pan. Sprinkle the cinnamon-sugar mixture evenly over the batter, then pour the remaining batter on top
Create the Marble EffectUsing a butter knife, gently swirl the batter in a figure-eight motion to create a ribbon effect. Don’t overdo it — you want visible layers.
Bake to PerfectionPlace in the preheated oven and bake for 50–60 minutes, or until a toothpick inserted into the thickest part comes out clean.
Cool & ReleaseAllow the cake to cool in the pan for 15 minutes before carefully inverting it onto a wire rack. Cool completely before glazing.
Optional GlazeWhisk together powdered sugar, milk, and vanilla until smooth. Drizzle over the cooled cake for extra sweetness and a polished look.
