Ingredients:
- 1/2 cup (100g) granulated sugar
- 1/4 cup (30g) all-purpose flour, plus more for dusting the pan
- 1/4 cup (25g) packed light brown sugar
- 1/4 cup (57g) cold unsalted butter, cut into small cubes
- 1/2 teaspoon ground cinnamon
- Pinch of salt
- 1 1/2 cups (192g) all-purpose flour, plus more for dusting the pan
- 1 teaspoon baking powder
- 1/2 teaspoon baking soda
- 1/4 teaspoon salt
- 1/2 cup (113g) unsalted butter, softened
- 3/4 cup (150g) granulated sugar
- 2 large eggs
- 3/4 cup (177ml) sour cream or plain yogurt
- 1 teaspoon vanilla extract
- 2 tablespoons (25g) granulated sugar
- 1 teaspoon ground cinnamon
Instructions:
- Prepare the Streusel: In a bowl, combine granulated sugar, brown sugar, flour, cinnamon, and salt. Cut in cold butter using a pastry blender or your fingers until the mixture resembles coarse crumbs. Set aside.
- Make the Cake Batter: Preheat oven to 350°F (175°C). Grease and flour a 9-inch round cake pan. In a separate bowl, whisk together flour, baking powder, baking soda, and salt.
- Cream Butter and Sugar: In a large bowl, cream together softened butter and granulated sugar until light and fluffy.
- Add Eggs and Vanilla: Beat in the eggs one at a time, then stir in the vanilla extract.
- Alternate Wet and Dry Ingredients: Gradually add the dry ingredients to the wet ingredients, alternating with the sour cream or yogurt, beginning and ending with the dry ingredients. Mix until just combined. Do not overmix!
- Assemble the Cake: Pour half of the batter into the prepared cake pan.
- Create the Cinnamon Swirl: In a small bowl, combine cinnamon swirl sugar and cinnamon. Sprinkle half of the cinnamon-sugar mixture over the batter in the pan.
- Layer and Top: Pour the remaining batter over the cinnamon swirl. Sprinkle the remaining cinnamon-sugar mixture and then the streusel topping evenly over the cake.
- Bake: Bake for 35-40 minutes, or until a wooden skewer inserted into the center comes out clean.
- Cool: Let the cake cool in the pan for 10 minutes before inverting it onto a wire rack to cool completely.