Place sugar, softened butter, cinnamon and salt in a small bowl and mix with a fork until crumbly. Remember, you do not want to cream this, it should be crumbly. Set aside (if it’s a hot day, place in refrigerator).
Muffin Batter
In large bowl cream butter and sugar. Once creamed add eggs and mix until well combined and fluffy.
In medium bowl combine flour, baking powder, baking soda and salt.
Add vanilla extract to milk and stir.
Add half of flour mixture and half of milk to butter and eggs. Mix until just combined (use Danish dough whisk if you have one). Add remaining flour and milk and mix just to combine. Fold in blueberries.
Fill each muffin 3/4 full and sprinkle tops with streusel. Bake until tester comes out clean, about 15 minutes for regular muffins (25 – 30 minutes for jumbo). Remove from pan to cool on rack. Enjoy!