Instructions:

Preheat your oven to 350°F (175°C). Grease and flour a 9×9-inch baking pan or a similar-sized cake pan.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set this dry ingredient mixture aside.

In a separate large mixing bowl, cream the softened butter and sugar together until light and fluffy.

Beat in the eggs one at a time, followed by the lemon zest, lemon juice, and vanilla extract.
Gradually add the dry ingredient mixture to the wet ingredients, alternating with the sour cream, beginning and ending with the dry ingredients. Mix until just combined.
Gently fold in the fresh blueberries.
Pour the cake batter into the prepared pan and spread it evenly.
Bake in the preheated oven for about 30-35 minutes, or until a toothpick inserted into the center comes out clean.
While the cake is baking, prepare the Lemon Creme Topping.