Gently fold in the fresh blueberries.
Pour the batter into the prepared cake pan, spreading it out evenly.
In a separate bowl, combine the flour, brown sugar, and chilled butter for the streusel topping. Use a fork or your fingers to mix until crumbly.
Sprinkle the streusel evenly over the cake batter.
Bake in the preheated oven for 35-40 minutes, or until a toothpick inserted into the center comes out clean.
Let the cake cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely.
For a zesty twist, add a teaspoon of lemon zest to the cake batter. You can also substitute the blueberries with raspberries or chopped strawberries for a different flavor profile. If you’re looking for a nutty texture, add some chopped walnuts or pecans to the streusel topping. For a gluten-free version, use a gluten-free flour blend. And if you’re in the mood for a little spice, a pinch of cinnamon or nutmeg in the batter can add a lovely warmth to the cake.