Step 1Place the butter, granulated sugar, brown sugar, cinnamon and salt in a food processor; process until crumbly. Set the topping aside in the refrigerator.
Step 1Place a rack in the center of the oven; heat the oven to 350 degrees. Grease a 10-inch springform pan and set it aside.
Step 2Use a mixer to cream the butter and sugar until fluffy. Add the cinnamon, vanilla and eggs. Mix until smooth. Add the sour cream. Mix well. Add the flour, reserving 2 tablespoons, then add the baking soda and salt. Mix the batter until smooth. Toss the blueberries with the remaining flour and stir them into the batter. Transfer the batter to the prepared pan, spreading evenly.
Step 3Bake the cake 25 minutes. Carefully bring the cake pan to the edge of the rack. Scatter the topping evenly over the cake. Continue to bake the cake until a toothpick inserted into the center comes out clean, about 25 minutes more.
Step 4Cool the cake on a wire rack at least 30 minutes before serving. (This can be made a day ahead and kept at room temperature, covered. To serve warm, reheat in a 300-degree oven until warm, about 12 minutes.) Use a sharp, flexible knife to separate the cake from the sides of the pan. Remove the ring. Serve in wedges.