The blueberries have been such sweet treats lately, they will be just beautiful in this moist cake, scented with cinnamon. But even when blueberry season ends, don't despair. Frozen blueberries work just as well; don't bother defrosting, just pop them right into the batter.
Preheat oven to 350°F. Butter and lightly dust with flour a 9 inch baking pan (I used a springform pan).
Sift or whisk together flour, baking soda, salt, and cinnamon and set aside. Cream butter and sugar together. Add vanilla and egg, mix well. Alternately stir in buttermilk and flour mixture. Gently fold in 1/2 cup blueberries. Pour into prepared cake pan and spread evenly with an offset spatula. Sprinkle the remaining blueberries on top. Bake for 25-30 minutes, until the top is golden brown and a toothpick inserted comes out clean. Serve with whipped cream (see instructions below).
Whisk heavy cream, sugar and maple syrup until soft peaks form. Add dollop to the cake right before serving.