Preheat oven to 325°F. Spray a 10-inch bundt pan with non-stick spray.
In the bowl of a stand mixer fitted with the paddle attachment, cream butter on medium speed until smooth. Gradually add the sugar and mix until light and fluffy.
Add eggs, one at a time, mixing well after each addition, scraping the bowl as needed.
Slowly add the cake flour. Mix on low until combined.
Add buttermilk. Mix until just incorporated, scraping the bowl as needed.
Add lemon extract, lemon zest, and fold in blueberries.
Pour batter into the prepared bundt pan. Bake for 85-90 minutes, or until a toothpick inserted into the center comes out with a few crumbs. Cool to room temperature before serving.
Notes
This cake is perfect served with a dusting of powdered sugar or a light glaze.