Did some shopping today and the first thing I saw were blueberries@ 99 cent a pint, you would not believe my joy. I used 2 for this wonderful cake and are freezing the rest on cookie sheets and bagging for the winter. My cake came out so moist, with the added buttermilk and juicy blueberries, try it out. You will not be disappointed.
Position a rack in the middle of the oven and preheat to 350 °. Butter pan, line the bottom of the pan with a round of parchment. Dust with flour and tap out excess, arrange berries in the bottom of the pan, then sprinkle evenly with a quarter cup of sugar.
Sift 2&1/3 cup of flour, baking powder, salt and baking soda into a medium bowl, set aside. Using an electric mixer beat 3/ 4 cup of sugar and remaining 1&1/3 cup of sugar at medium-high speed, scraping down the sides of the bowl until pale and fluffy, about 2 minutes.
Add eggs one at a time, beating well after each addition, beat in vanilla and zest, reduce speed to low.
Beat in flour mixture in 3 additions alternating with buttermilk in 2 additions, beginning and ending with flour mixture until just incorporated. Pour batter over berries and smooth top.
Bake until cake is golden brown and a tester inserted comes out fairly ckean, about 1 hour and 25 minutes, (my cake took 1 hour, 8 minutes, depending on your stove, so watch carefully, your tester should not be crumb free, that means the cake is too dry.
Let cool in the pan, on a wire rack for 15 minutes, then run a thin sharp knife around the edges to loosen. Invert cake onto rack and dust with powdered sugar, cool completely.