Preheat oven to 350 degrees. Butter an 8” or 9” springform pan, then butter a parchment paper round that you place at the bottom of the pan. Use flour to dust the inside ofthe cake pan and tap out any excess.
Layer the bottom of the pan with the turbinado sugar and then add the blackberries.
In a medium bowl, add together the dry ingredients (flour, corn meal, baking soda and salt) and whisk until combined.
In another large bowl, use an electric handheld mixer or standing mixer with paddle attachment to beat the sugar and butter togetheruntil they are light and fluffy and well creamed (beat for about 4-5 minutes).
Add the eggs one at a time and beat well until incorporated,then add the vanilla.
Add the flour mixture and the buttermilk to the bowl inthree batches until combined. Mix until just combined, but don’t overwork thebatter.
Pour the batter over the berries and gently smooth the top without pushing down on the batter.
Bake in the middle of the oven for 40 minutes,or until a cake tester inserted in the top portion of the cake comes out clean. Be careful if it touches the berries, it will come out blue! Just test the cake portion.
Remove the cake from the oven and let cool for about 15 to 20 minutes.
Run a paring knife around the edge of the cake pan and remove the outside of the cake pan. Invert the cake onto a plate or cutting board and carefully peel off the parchment paper. Serve warm or at roomtemperature.