Preheat oven to 350 degrees . Spray a 10-inch springform pan with cooking spray. Mark the edge of the pan into 12 parts. Stir together flour, cornmeal, sugar, baking powder, baking soda, and salt. Crush the dried rosemary between your fingers into the dry ingredients. Mix together the sour cream, buttermilk, melted butter, and eggs. Add to the dry ingredients and mix until just moistened. Do not overmix. Spread ⅓ of the mixture onto the bottom of the pan. Place 12 sausages on top, lining them up with the 12 marks on the pan. Spoon ⅓ mixture on top of sausages and spread, careful not to move the sausages. Distribute blueberries. Top with remaining ⅓ of mixture and then lightly press the remaining 12 sausages into the top, again lining them up with the 12 marks. Bake for 1 hour. Check with a toothpick at 45 minutes.