Preheat oven:
Set oven to 350°F (175°C). Grease and flour an 8-inch round cake pan or bundt pan.
Mix dry ingredients:
In a medium bowl, whisk flour, baking powder, baking soda, and salt. Set aside.
Cream butter and sugar:
In a large mixing bowl, beat butter and sugar together until pale and fluffy, about 2–3 minutes.
Add eggs and flavoring:
Beat in eggs one at a time. Add lemon zest, lemon juice, and vanilla extract.
Combine batter:
Add dry ingredients in two parts, alternating with buttermilk. Mix until just combined.
Fold in blueberries:
Gently fold in flour-coated blueberries using a spatula.
Bake:
Pour batter into the prepared pan and bake for 40–45 minutes, or until a toothpick inserted in the center comes out clean.
Cool and glaze:
Allow the cake to cool for 10 minutes, then drizzle with lemon glaze. Garnish with fresh blueberries or lemon slices if desired.