Preheat your oven to 350°F (175°C). This will ensure the cake bakes evenly.

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.

In a large mixing bowl, cream the softened butter and granulated sugar until light and fluffy, about 3-5 minutes.

Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.

Gradually add the dry mixture into the butter mixture, alternating with the buttermilk. Start and end with the flour mixture, mixing until just combined.

In a small bowl, toss the blueberries with cornstarch until they are well coated.

Gently fold the blueberries into the cake batter, being careful not to crush them.

Pour the batter into a greased and floured cake pan (a 9×13 inch works great). Smooth the top with a spatula.

Bake in the preheated oven for 30-35 minutes. The cake is done when a toothpick inserted into the center comes out clean, and it has a beautiful golden color.

Allow the cake to cool in the pan for about 10 minutes, then transfer it to a wire rack to cool completely.

Dust with powdered sugar before serving.