01 -
Preheat the oven to 175°C (350°F). Grease and flour a 9-inch round cake pan or line it with parchment paper.
02 -
In a small bowl, mix together sugar, flour, and cinnamon. Cut in the cold butter using a pastry cutter or your fingers until the mixture resembles coarse crumbs. Set aside.
03 -
In a medium bowl, whisk together flour, baking powder, baking soda, and salt. In a large mixing bowl, cream the softened butter and sugar until light and fluffy. Beat in the eggs, one at a time. Mix in the sour cream and vanilla extract until smooth. Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Gently fold in the blueberries.
04 -
Pour the batter into the prepared cake pan, spreading it evenly. Sprinkle the streusel topping over the batter.
05 -
Bake for 40-45 minutes, or until a toothpick inserted into the center comes out clean and the top is golden brown. Allow the cake to cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.
06 -
Enjoy the cake warm or at room temperature with your favorite coffee or tea.