Preheat oven to 375. Line 12 muffin cups with liners. In a bowl, whisk 2 cups flour, baking soda and salt. In a mixing bowl beat 1 stick of softened butter and 1 cup of sugar until blended well. Add in the eggs one at a time and scrape down sides of bowl as necessary. Beat in vanilla. Add the flour mixture, alternating with milk. Fold in the blueberries to the batter. Do not overmix. Spoon batter into muffin tin liners. Topping: In a bowl mix 1/2 cup sugar, 1/3 cup flour, 1/4 cup softened butter and 2 teaspoons of cinnamon. Mix with a fork or pastry blender. Sprinkle generously over muffins before baking. Bake muffins for about 30 minutes. Tops will be golden brown and cake tester should come out clean. Cool muffins on a rack for 10 minutes before serving.