Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans or line the bottoms with parchment paper.
In a large mixing bowl, cream together the softened butter and granulated sugar using a stand mixer or hand mixer until light and fluffy, about 3-5 minutes.
Add the eggs one at a time, mixing well after each addition. Then, stir in the lemon zest and lemon juice.
In another bowl, whisk together the flour, baking powder, baking soda, and salt. Gradually add this dry mixture to the wet mixture, alternating with the buttermilk. Begin and end with the dry ingredients. Mix until just combined.
Gently fold in the blueberries using a rubber spatula, being careful to not break them.
Divide the batter evenly between the prepared pans and smooth the tops.
Bake in the preheated oven for about 30-35 minutes, or until a toothpick inserted in the center comes out clean.
Allow the cakes to cool in the pans for 10 minutes, then turn them out onto a cooling rack to cool completely.
Once cool, you can dust the cakes with powdered sugar or prepare a simple lemon glaze by mixing powdered sugar with lemon juice until desired consistency. Drizzle the glaze over the cake before serving.