I am always on a quest for a great muffin recipe and this one nails it! I have even make them with cranberries, when I use cranberries I add a the zest of one orange as well. They are a little work but well worth the extra time of making these.
Preheat oven to 350, place cup cake papers in muffin tin. Now start by making your streusel topping
Combine all items for streusel topping and using either a pastry blender or a couple knifes blend till it is crumbly. Set aside and make the muffin batter
Combine flour, baking powder and salt in bowl and whisk together and set aside.
In mixing bowl combine softened butter and sugar, mix for 4 to 5 minutes. Mixture will be very light in color. Turn mixer to low speed and add eggs one a time, blending each one in, than add vanilla extract.
Add half of the flour mixture and half of the buttermilk and mix lightly, you can do this by hand if you like. Now add the remaining flour mixture and buttermilk and mix together. Add blueberries and gently fold in. Divide batter into muffin cups, filling cups about 3/4 full. Now take and sprinkle streusel topping on top of muffins. I like using lots on mine, but its up to you as to how much as you like. To me the more the better! Bake at 350 for 28 to 30 minutes. I start checking mine at 25 minutes. If you have extra streusel topping just place in a freezer bag and store in the freezer for future use. I like to make jumbo muffins so I double the recipe.