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:

  1. 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.
  2. 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.
  3. Cream Butter and Sugar: In a large bowl, cream together softened butter and granulated sugar until light and fluffy.
  4. Add Eggs and Vanilla: Beat in the eggs one at a time, then stir in the vanilla extract.
  5. 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!
  6. Assemble the Cake: Pour half of the batter into the prepared cake pan.
  7. 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.
  8. 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.
  9. Bake: Bake for 35-40 minutes, or until a wooden skewer inserted into the center comes out clean.
  10. Cool: Let the cake cool in the pan for 10 minutes before inverting it onto a wire rack to cool completely.